Hogwarts staff

The following fictional characters are staff members and denizens of Hogwarts in the Harry Potter books written by J. K. Rowling.

Notable teachers and staff members
The following are notable teachers and staff members who do not have their own articles or who are not listed in other articles.

Argus Filch
Argus Filch is the caretaker of Hogwarts. While he is not an evil character, he is ill-tempered, which makes him very unpopular with the student body, and occasionally with other staff. His knowledge of the secrets and short-cuts of the castle is almost unparalleled, except perhaps by the Weasley twins, and other users of the Marauder's Map. He tends to favour almost sadistically harsh punishments, leading to his alliance with Dolores Umbridge. He has an obsessive dislike of mud, animate toys, and all other things that might interfere with his creation of an immaculately clean and orderly Hogwarts. He is also portrayed as having a constant antagonism towards Peeves the poltergeist and often tells Dumbledore that Peeves should be thrown out of Hogwarts.

Filch is revealed to be a Squib in Harry Potter and the Chamber of Secrets when Harry Potter accidentally discovers that he is trying to teach himself basic magic from a Kwikspell correspondence course. Nonetheless, Filch is at least able to use wizarding devices that have their own innate magic, such as the Secrecy Sensor used in Harry Potter and the Half-Blood Prince. It is hinted that his dislike of students may stem from his disappointment and jealousy at not being able to do magic. In the Half Blood Prince, Harry Potter and Hermione Granger jokingly suspect that he is in a relationship with Irma Pince, the librarian at Hogwarts. In Harry Potter and the Deathly Hallows, the final book, when the school starts preparing itself for the Battle of Hogwarts, Filch is seen yelling that students are out of bed. He is later seen overseeing the evacuation of younger students.

Filch has a cat named Mrs. Norris to whom he has a particular and possessive attachment. She acts as a hallway monitor or spy for Filch. If she observes students engaging in suspicious activity or out of bed after curfew, she finds Filch and he arrives in seconds. She has been known to follow Hagrid everywhere he goes in the school, apparently under Filch's orders. According to J.K. Rowling, there is nothing particularly magical about Mrs. Norris, other than her being "just an intelligent (and unpleasant) cat." It's the ambition of many Hogwarts students to "give her a good kick". In the Chamber of Secrets incident, Mrs. Norris is temporarily petrified by the Basilisk, which causes Filch extreme distress.

David Bradley portrays Filch in the film series. Mrs. Norris was played by a Maine Coon cat named Peebles.

Filius Flitwick
Filius Flitwick is the Charms Master at Hogwarts and the head of Ravenclaw, and is described as being very short. He is also mentioned as a model student and a former duelling champion. In Harry Potter and the Philosopher's Stone he uses his magical skills to help decorate the Great Hall for Christmas. He is also one of the teachers who casts spells to guard the Philosopher's Stone by putting charms on a hundred keys so they can fly, making it difficult to find the key to the door leading to the next chamber.

During Harry's second year, Flitwick helps Professor Sinistra carry a petrified Justin Finch-Fletchley to the hospital wing. He teaches the front doors to recognise a picture of Sirius Black after his second break-in in Harry Potter and the Prisoner of Azkaban. He helps patrol the perimeter of the maze for the third task of the Triwizard Tournament held in Harry's fourth year. He eventually removes most of the swamp that is created within the school by Fred and George Weasley in Harry Potter and the Order of the Phoenix, though he previously leaves the swamp untouched to annoy Professor Umbridge. He does however, choose to leave a small patch of it behind, because he thinks it is "a good bit of magic" and a tribute to the Weasley twins. Near the end of Half-Blood Prince, Flitwick is sent by Professor McGonagall to ask Snape to come to the aid of the Order of the Phoenix against the intruding Death Eaters. He either collapses or is stunned by Snape after requesting his help at the battle.

In Harry Potter and the Deathly Hallows, Flitwick insists that Rowena Ravenclaw's Diadem is lost, and he is described by Harry (along with Dumbledore) as having been a "model student" who supposedly never entered the Room of Hidden Things, and so it never occurred to him that the diadem could be hidden there. Before the Battle of Hogwarts, Flitwick helps to put protective charms around the castle to hinder Lord Voldemort and his oncoming Death Eaters, and later fights the intruders in the battle, battling Yaxley and later defeating Antonin Dolohov.

In the film adaptations, Flitwick is portrayed by Warwick Davis. Rowling said: "I must admit, I was taken aback when I saw the film Flitwick, who looks very much like a goblin/elf (I’ve never actually asked the film-makers precisely what he is), because the Flitwick in my imagination simply looks like a very small old man." However, Rowling mentions on her official website that Flitwick is human, with "a dash of goblin ancestry." His on-screen appearance changes noticeably in Harry Potter and the Prisoner of Azkaban, in which he takes on a more human and less elf-like look, with slicked-down dark hair and moustache. According to Davis, the moustachioed character was originally not supposed to be Flitwick; Flitwick was absent from the script for Harry Potter and the Prisoner of Azkaban, but "the producer" (presumably David Heyman) added the new character (as the conductor of the school choir and orchestra, credited as "Choir Master") so that Davis could still appear in the film. Goblet of Fire director Mike Newell preferred the new look, "and from that moment, the character became known as 'Flitwick'."

Flitwick was born on 17 October, but the year of his birth is never mentioned in the books or films.

Gilderoy Lockhart
Gilderoy Lockhart is a narcissistic wizarding celebrity who has written many books on his fabulous adventures (which turn out not to be true) encountering dark creatures. In Chamber of Secrets, Lockhart is appointed as Hogwarts's new Defence Against the Dark Arts instructor. He is unpopular amongst most of the staff, particularly Professor Snape; however, he is greatly admired by many others, particularly witches, such as Hermione Granger and Mrs. Weasley, who find him attractive. Harry dislikes Lockhart for a number of reasons: his arrogance, his belief that Harry flew to Hogwarts in a car to seek further attention, his penchant for handing out signed photos of himself, and the trouble he has with simple magic such as healing Harry's broken arm—he accidentally removes all of Harry's arm bones instead. Lockhart is exposed as a charlatan and a coward when he attempts to avoid entering the Chamber of Secrets by revealing to Harry and Ron Weasley that he never performed the amazing feats documented in his books, instead stealing other wizards' experiences and erasing their memories. His attempt to use a Memory Charm on Harry and Ron backfires due to his use of Ron's broken wand, and he suffers the permanent near-total amnesia as a result.

In Order of the Phoenix, Harry comes across Lockhart in St Mungo's while visiting Mr. Weasley at Christmas. Lockhart is slowly regaining his memory and is childishly proud of being able to write in "joined-up letters". He still enjoys signing autographs and still receives fan mail, although he has no idea why. Lockhart never fully recovers, despite all efforts to cure him.

Rowling has said Lockhart is the only character she has ever based on a real-life person. Lockhart was inspired by an unrevealed acquaintance who was "even more objectionable than his fictional counterpart" and "used to tell whopping great fibs about his past life, all of them designed to demonstrate what a wonderful, brave and brilliant person he was."

Kenneth Branagh portrayed Lockhart in the film version of Chamber of Secrets. In a scene after the end credits, his latest book is on sale in Diagon Alley; entitled Who Am I?, it displays a picture of him humming distractedly to himself and wearing a straitjacket.

Minerva McGonagall
Minerva McGonagall is Deputy Headmistress, head of Gryffindor House, Transfiguration professor, and later Headmistress at Hogwarts, where she began teaching in December 1956. She is first introduced in the opening chapter of Harry Potter and the Philosopher's Stone, when she meets Dumbledore at Number 4 Privet Drive, Little Whinging, Surrey (the home of Harry Potter's aunt and uncle, Vernon and Petunia Dursley). McGonagall is described as a tall, rather severe-looking woman, with black hair typically drawn into a tight bun. She wears emerald green robes, a pointed hat, and always has a very prim expression. She speaks with a slight Scottish accent. She is, according to Rowling, a sprightly 70-year-old. McGonagall wears square spectacles that match the markings around the eyes of her Animagus form of a silver tabby cat; she has the distinction of being the first Animagus introduced in the series and being one of the few registered Animagi of the century, though she was rarely seen using the ability. Harry's immediate impression of her is of someone who is not to be crossed. She has a fondness for tartan, and her handkerchief, at least one hat, dressing gown, and dress robes are patterned with it. McGonagall often wears a Scottish brooch in the Cairngorm style. Rowling has said McGonagall's birthday is 4 October.

In the first book, after seeing Harry fly masterfully his very first time on a broom, she recommends him to fill the position of Seeker on the Gryffindor Quidditch team and sends him a broom, even though first-year students are normally prohibited from playing the sport or owning brooms. Furthermore, although a rigorous disciplinarian, she often assists Harry indirectly with activities that are not strictly within the rules of Hogwarts; for example, she allows Harry and his friends to use the Transfiguration classroom to practice for tasks in the Triwizard Tournament. She promises Harry she would do everything in her power to help him to achieve his goal of becoming an auror, and she keeps her promise. Despite her stern front, McGonagall is shown to have good intentions at heart and has been known to display a range of emotions, which can often be a shock to her colleagues and students.

It is revealed in Order of the Phoenix that McGonagall is a member of the Order of the Phoenix. She and Dolores Umbridge seem to have a mutual dislike for each other, as Umbridge continuously usurps more and more power from the staff and from Dumbledore and McGonagall in particular. When McGonagall attempts to stop Umbridge and her fellow Ministry cronies from unjustly taking Hagrid away by force, she is hit by four stunning spells without warning, before she can draw her wand. In an unconscious state, she is rushed to St Mungo's, where she recovers for awhile. McGonagall returns to the school towards the end of the book, though she temporarily uses a walking stick to support herself. After the death of Dumbledore in Half-Blood Prince, she becomes the acting Headmistress of Hogwarts.

However, in the series finale, she does not become headmistress at the start of term as expected; Snape is appointed by the new Minister for Magic Pius Thicknesse, who is actually under the Imperius Curse and acting for Voldemort. Despite the many changes, she is retained as head of Gryffindor House. Before the Battle of Hogwarts, she goes to the Ravenclaw tower and finds Alecto Carrow stunned and her brother Amycus searching for Harry. When Amycus suggests hurting the students to compensate for his sister's state, McGonagall immediately intervenes. In response, Amycus spits in her face. Harry, who is present and hidden under his invisibility cloak, reveals himself and uses the Cruciatus Curse on Amycus. Harry then informs McGonagall that Voldemort is on his way and after tying up both the Carrows and placing them in a net, she sends three Patronuses – which manifest in her Animagus form – to warn the other three Heads of House. When on her way to meet the Heads of House, she meets Snape, who questions her about Potter's whereabouts. Not knowing Snape is actually still following Dumbledore's orders and has important information for Harry, she attacks him, engaging in a fierce duel. With help from Professors Sprout and Flitwick, she succeeds in driving Snape away. McGonagall then takes charge of the school again and proceeds to secure it against Voldemort to ensure Harry can fulfil his mission from Dumbledore. She also organises the evacuation of the school's under-age students to ensure their safety. She then leads the remaining students, the staff of Hogwarts, and members of the Order of the Phoenix in the fight against Voldemort. She is seen during the battle with a large gash on her cheek and commanding a herd of charmed desks to charge at Death Eaters. When Harry has been apparently killed, she screams, causing Bellatrix Lestrange to laugh. Finally, McGonagall ends up duelling Voldemort alongside Kingsley Shacklebolt and Horace Slughorn. As is confirmed in The Tales of Beedle the Bard, McGonagall becomes Headmistress of Hogwarts after the Battle of Hogwarts and Snape's death; however, in an interview Rowling said McGonagall would be retired by the time of the Deathly Hallows epilogue (19 years after the main events of Deathly Hallows), as she is "getting on in years."

McGonagall is played by Dame Maggie Smith in the film adaptations. Smith has described her role as "Miss Jean Brodie in a wizard's hat", Given that her role becomes progressively smaller as the series goes on, she notes that Harry Potter and the Philosopher's Stone is her favourite thus far. Smith appeared in all the films of the series except for Harry Potter and the Deathly Hallows – Part 1, which does not take place in Hogwarts. Rowling has stated that she always pictured Smith portraying McGonagall, and claimed the actress to be at the top of her list.

Rowling named the character after the poet William Topaz McGonagall, whose name she liked. Her first name, Minerva, comes from the Roman goddess of wisdom.

Poppy Pomfrey
Madam Poppy Pomfrey is a magical Healer who is the matron-in-charge of the Hogwarts hospital wing. She is known to be very strict regarding the rules of her infirmary. Ron goes to Madam Pomfrey after being bitten by a dragon named Norbert in Harry Potter and the Philosopher's Stone. After Harry defeats Professor Quirrell in the dungeons, he spends three days unconscious in the hospital wing. In Chamber of Secrets, Madam Pomfrey regrows the bones in Harry's broken arm after Gilderoy Lockhart accidentally removes them following Gryffindor's Quidditch win over Slytherin. Hermione ends up in the hospital wing for a month after a mishap with the Polyjuice Potion that leaves her half-feline, then is again hospitalised after she is petrified along with several other students. In Prisoner of Azkaban, Madam Pomfrey speaks approvingly of Remus Lupin's use of chocolate to relieve the effects of a dementor's presence on students, commenting that Hogwarts has "finally got a Defence Against the Dark Arts teacher who knows his remedies". She also tended to Harry after the Quidditch match against Hufflepuff, due to dementors around the pitch. After Umbridge's guards stun McGonagall in Order of the Phoenix, Madam Pomfrey says she would resign in protest were she not afraid of what would become of the students without her presence. She also tends to Hermione, Ginny, Ron, Harry, Neville, and Luna after the battle in the Department of Mysteries. Umbridge is also a recipient of her healing skills after her scuffle with the Centaurs. In Half-Blood Prince, she takes care of Ron after he is poisoned and tends to Harry after his skull is cracked by a Bludger in a Quidditch match. She attempts to heal Bill of his scars from Greyback's attack, without much success, and bursts into tears when she hears of Dumbledore's death. In Deathly Hallows, she and Argus Filch oversee student evacuations from Hogwarts before the Battle of Hogwarts. She is later seen tending to the injured fighters.

Gemma Jones appeared as Madam Pomfrey in the film adaptations of Chamber of Secrets, Half Blood Prince, and Deathly Hallows – Part 2.

Quirinus Quirrell
Quirinus Quirrell is the Defence Against the Dark Arts teacher at Hogwarts during Harry Potter's first year. Prior to his employment at Hogwarts, he is said by Rubeus Hagrid to have had a "brilliant mind", and was a fine teacher while studying from books; some time before Harry's arrival at Hogwarts, "he took a year off to get some first-hand experience". Rowling stated in a live web chat on 30 July 2007 that Quirrell had worked at Hogwarts as Muggle Studies teacher for a certain length of time, before taking the cursed Defence Against the Dark Arts position in the same year that Harry joined. Upon his return, he appears perpetually nervous and has developed a stutter and nervous tics. Quirrell's attire includes a new purple turban which he claims to have received as a reward from an African prince for getting rid of a troublesome zombie. Fred and George Weasley constantly joke that the turban was full of garlic.

Harry first meets Quirrell at the Leaky Cauldron, while being escorted by Hagrid to Diagon Alley to shop for school supplies. Quirrell is next seen at Hogwarts conversing with Snape at the start-of-term banquet, and then regularly while teaching Defence Against the Dark Arts lessons. During the school's Halloween banquet, Quirrell appears in the Great Hall to warn staff and students of a troll in the dungeons and then he faints. While playing Quidditch, Harry is almost thrown off his broom by some sort of curse and he, Ron, and Hermione believe it is Snape who is responsible. They begin to suspect that Snape is trying to steal the Philosopher's Stone hidden in a secret chamber in Hogwarts; however, when Harry finally arrives in the chamber, he discovers that it is not Snape, but Quirrell, who is the real villain. Quirrell then reveals that he was the one who let in the troll and attempted to throw Harry off his broom while Snape muttered a counter curse. During the climax of the story, as Harry and Quirrell try to recover the stone from the Mirror of Erised, Voldemort reveals himself on the back of Quirrell's head, formerly concealed by the turban, and speaks directly to Harry, threatening to kill him if he does not assist Voldemort in recovering it. After Harry refuses, Voldemort orders Quirrell to attack Harry, who holds off Quirrell long enough for aid to arrive, at which point Voldemort flees, in his non-physical form. Voldemort's departure, as well as the agony suffered by him because of his contact with Harry, who continues to be protected by the love of his mother and the spell that was cast by her sacrificing her life to save Harry, causes Quirrell to die. It is later revealed in the chapter The Prince's Tale from Harry Potter and the Deathly Hallows that Snape was actually keeping an eye on Quirrell under Dumbledore's orders.

British actor Ian Hart portrayed Quirrell in the first film.

Horace Slughorn
Horace E. F. Slughorn is the long-serving Potions teacher and Head of Slytherin House since at least the 1940s, until his retirement after the 1980–81 school year. Following his retirement and the resurgence of Voldemort, Slughorn goes into hiding, concealing all knowledge of his whereabouts from both sides in the growing conflict in the wizarding world. However, after moving Snape to Defence Against the Dark Arts, Dumbledore locates Slughorn and uses Harry as incentive to convince him to return to teaching Potions. Slughorn is described as preferring to be a "back-seat driver", obtaining things he desires by using his contacts, particularly students whom he has invited into the "Slug Club", a group of students favoured by Slughorn, based either on their connections to important people or on his belief that they have traits that will make them important and famous themselves when they leave school such as Gwenog Jones who is the captain of the all-female quidditch team, the Holyhead Harpies; The benefit from this is that he acquires free season tickets whenever he wants them. He is one of the first Slytherin characters to defy the house's stereotype: while he is self-serving and not above bending rules, he lacks the near-amorality and underhandedness that had, until that point, been a hallmark of the house. He does not resent blood status in general, and admits a pleasurable surprise when he comes upon a talented Muggle-born, such as Hermione or, years before, Lily Evans, one of his all-time favourite pupils. Also, Slughorn notably displays not pride, but shame at having helped a young Tom Marvolo Riddle perform some of his most noted and impressive feats of magic, as Riddle had questioned Slughorn about Horcruxes. However, students he deems unimportant he ignores, as though they were not there.

In Half-Blood Prince, Harry is invited to the first meeting of the Slug Club held on the Hogwarts Express. Slughorn sets less-stringent entry criteria for Advanced Potions than his predecessor, lowering the required grade from a perfect O (Outstanding) to the above-average E (Exceeds Expectations). This last-minute change enables Harry and Ron to take Potions at NEWT level. However, since Harry had not expected to be allowed to join the course, he has none of the necessary materials, and Slughorn lends him an old textbook until Harry can procure his own. Later, Harry does buy a new copy of Advanced Potion-Making from Flourish and Blotts, but switches the covers and gives back the new book. During his first class, Slughorn offers a small amount of Felix Felicis to the student who brews the best cauldron of the Draught of Living Death. Harry wins with the help of handwritten notes in the borrowed textbook, which had once belonged to Snape. When Ron Weasley falls victim to a high-strength love potion, Slughorn administers an antidote but then nearly kills him with a drink of poisoned mead, not knowing that the bottle had been planted by Draco Malfoy in an attempt to kill Albus Dumbledore. Harry later uses the Felix Felicis to retrieve a memory from Slughorn that details the conversation between the professor and Riddle about Horcruxes as well as the possibility of creating more than one Horcrux.

In Harry Potter and the Deathly Hallows, Slughorn briefly appears with other teachers assembling to fight Death Eaters. As Snape is now Headmaster, Slughorn has assumed the post of Head of Slytherin. Though he is initially hesitant to join in the Battle of Hogwarts and is assumed to have evacuated with his house, he returns to the fray later on. It is revealed that he has not fled, but has recruited a large number of reinforcements to fight for Hogwarts. He then summons up the courage to duel Voldemort, alongside McGonagall and Kingsley Shacklebolt.

Slughorn is played by Jim Broadbent in the film adaptations of Harry Potter and the Half-Blood Prince and Harry Potter and the Deathly Hallows – Part 2.

Pomona Sprout
Pomona Sprout is Professor of Herbology and the Head of Hufflepuff House. She is described as a dumpy little witch with flyaway grey hair who wears a patched, frayed hat and shabby robes, often covered in dirt due to the time she spends tending plants in the Hogwarts greenhouses. Sprout is introduced in Philosopher's Stone, but she plays no active role until Chamber of Secrets, in which she teaches her second year students to work with Mandrake plants. She is responsible for raising the Mandrakes to full maturity, at which point their juice is used to revive the petrified victims of the basilisk.

Sprout subsequently appears in Goblet of Fire in which, as the Hufflepuff Head of House, she comforts Amos Diggory and his wife after the death of their son, Hufflepuff student Cedric Diggory, whom she knew well. In Order of the Phoenix, Sprout is a non-vocal supporter of Harry's story about Voldemort's resurrection. Like many teachers at Hogwarts, she detests Umbridge's presence and does her best to disobey her. After the raid of Hogwarts in Half-Blood Prince, Sprout is a staunch advocate of keeping Hogwarts open. She also supports the suggestion that Dumbledore should be laid to rest at Hogwarts. Sprout attends Dumbledore's funeral, where she appears cleaner than she has ever been seen before.

In Deathly Hallows, she chases Snape away from Hogwarts with Professors McGonagall and Flitwick. Informed that Voldemort and his Death Eaters are coming to besiege Hogwarts, she uses her knowledge of magical plants by improvising offensive botany, and, with the help of several students, throws Mandrakes and Venomous Tentaculas off the castle walls at the approaching Death Eaters. The epilogue of Deathly Hallows reveals that Neville Longbottom has become the new Herbology teacher at Hogwarts. The circumstances of Sprout's departure from the job are not revealed.

Sprout was portrayed by Miriam Margolyes in the film adaptation of Chamber of Secrets and Deathly Hallows – Part 2.

Sybill Trelawney
Sybill Patricia Trelawney is the professor of Divination. She is the great-great-granddaughter of the celebrated seer Cassandra Trelawney, and, in fact, has inherited some of her ancestor's talent. Trelawney is described as a slight woman resembling an insect, draped in a large spangled shawl and many gaudy bangles and rings. She speaks in a misty voice and wears thick glasses, which cause her eyes to appear greatly magnified. Her odd classroom in the North Tower of Hogwarts is a cross between "someone's attic and an old-fashioned tea shop"; it can only be reached by climbing to the top of the stairs and then up a ladder through a trapdoor set in the ceiling. This dim, heavily scented, and "stiflingly" warm room often affects students' wakefulness.

Trelawney first appears in the third book of the series, when Harry, Ron, and Hermione start divination lessons. The friends generally believe Trelawney is a fraud. However, Gryffindor students Parvati Patil and Lavender Brown are very fond of and impressed by her. According to McGonagall, her credibility as a seer is undermined by her habit of erroneously predicting, each year, the death of one of her students. However, from time to time she does make predictions within the books, which come true. Her more profound predictions seem only to happen when she is in a trance and unaware of what she is saying, with no memory of it afterward.

Prior to the events of the Harry Potter books, Trelawney falls into a prophetic trance while in an interview with Dumbledore at the Hog's Head, making a prophecy about the birth of a wizard "with the power to vanquish" Voldemort. This prophecy was partly overheard by Snape, who relayed what he heard to Voldemort. This led Voldemort to attack the Potter family, believing that Harry was the child named. In Harry Potter and the Prisoner of Azkaban, Trelawney prophesies to Harry about the events of the book's climax. In Order of the Phoenix, Trelawney is first put on probation by Umbridge, and later fired. However, Trelawney continues to reside in Hogwarts castle due to an order by Dumbledore, who believes that she would be in danger outside of Hogwarts due to the prophecy she made during her interview. Dumbledore later reveals that the prophecy is why he keeps her employed as a Divination teacher. Trelawney returns to teaching in Half-Blood Prince, but has to share classes with Firenze, as he was cast out by his fellow centaurs when he agreed to replace Trelawney after she was fired. In Harry Potter and the Deathly Hallows, she is seen aiding in the Battle of Hogwarts by magically accelerating her crystal balls at Death Eaters. She uses one of these crystal balls to defend an injured Lavender against the attack of werewolf Fenrir Greyback. In the film adaptation, Harry Potter and the Deathly Hallows – Part 2, she is seen covering someone's body, with the aid of Padma Patil.

In the British editions of the books, her name is consistently spelled as "Sybill". In the American editions, from her first appearance in Prisoner of Azkaban through Order of the Phoenix, her name is spelled as "Sibyll". However, in the American edition of Half-Blood Prince, it is re-spelled as "Sybill", matching the UK edition.

Trelawney is portrayed by Emma Thompson in the Prisoner of Azkaban, Order of the Phoenix, and Deathly Hallows Part 2.

Hogwarts ghosts
Hogwarts is home to at least twenty ghosts, but when people in the novels speak of the ghosts at Hogwarts they are usually referring to one of the four resident ghosts of the Hogwarts houses: Sir Nicholas de Mimsy-Porpington (or, as the students refer to him, Nearly Headless Nick), the almost-decapitated wizard of the Court who resides in Gryffindor tower; the Bloody Baron, who resides in the Slytherin dungeon; the jovial Fat Friar, who resides with the Hufflepuffs; and the Grey Lady, who "lives" with the Ravenclaws. These ghosts seem to act as something like advisers and aides to the students; Nick is frequently seen helping Harry during moments of uncertainty or crisis. Another ghost mentioned frequently is Moaning Myrtle.

The Bloody Baron
The Bloody Baron is the Slytherin House ghost. He is the only person besides Dumbledore and Fred and George Weasley who can exert any control over the poltergeist Peeves; Peeves is terrified of him for some unknown reason, referring to him as "Your Bloodiness" and "Mr. Baron."

The Baron's nickname comes from the fact that he is covered with blood, which appears silvery on his ghostly form. When Nearly Headless Nick is asked in the first book why the Baron is so bloody, Nick delicately comments that " [he has] never asked". However, this is explained in Harry Potter and the Deathly Hallows, when Helena Ravenclaw tells Harry that the Baron had been in love with her when the two were alive, and when she ran off with her mother's diadem, Rowena Ravenclaw sent the Baron after her, knowing he would not stop until Helena was found. When Helena refused to return with him, however, the Baron killed her in a fit of rage, and then, in remorse, killed himself with the same weapon. He has thus haunted Hogwarts ever since, wearing his ghostly chains as a form of penance.

Terence Bayler portrayed the Baron in the first film. In contrast to his book counterpart, the Baron is quite mirthful in the film, playfully swiping through the Sorting feast with his sword, much to the amusement of those within his house.

The Fat Friar
The Fat Friar is the Hufflepuff House ghost. He is a jolly man and very forgiving. In Harry Potter and the Philosopher's Stone when the first years are waiting for Professor McGonagall to return and the ghosts pass overhead, the Fat Friar is pleading on behalf of Peeves the Poltergeist to allow him to come to the welcome feast despite his past wrongdoings. Similarly, when Peeves wants to join the welcome feast in Harry Potter and the Goblet of Fire, the Fat Friar was willing to give him a chance.

Simon Fisher-Becker appeared as the Fat Friar in the film adaptation of Philosopher's Stone.

The Grey Lady
The Grey Lady is the Ravenclaw House ghost. According to a letter written by Rowling to Nina Young, the actress who played the Grey Lady in the first film, she is "a highly intellectual young lady .... She never found true love as she never found a man up to her standards".

In Harry Potter and the Deathly Hallows it is revealed that the Grey Lady is Helena Ravenclaw, daughter of Rowena Ravenclaw, making her the only house ghost known to be related to one of the Hogwarts founders. She informs Harry that she stole the Diadem of Ravenclaw from her mother, in an attempt to become smarter than her, and then went into hiding in Albania. It was a dying Rowena Ravenclaw's wish to see her daughter again and so she sent for the Bloody Baron to look for her, knowing that he would not rest until he brought her back, partly because he was in love with her. However, she refused to come with him and, in a moment of blind rage, he killed her with a single stab wound to the chest. Overcome with remorse, the Bloody Baron killed himself using the same weapon in turn and wears chains as penitence, "as he should", the Grey Lady says. The diadem remained in the hollow of a tree in an Albanian forest until Tom Riddle managed to charm the story out of her ghost, the Grey Lady. Riddle, who had been seeking out historically significant objects to make into Horcruxes, later retrieved the diadem from Albania and hid it in the Room of Requirement at Hogwarts while visiting the castle years later.

In Harry Potter and the Deathly Hallows – Part 2, she was played by Kelly Macdonald, and in Harry Potter and the Philosopher's Stone the Grey Lady was played by Nina Young.

Nearly Headless Nick
Sir Nicholas de Mimsy-Porpington, often referred to as Nearly Headless Nick, Nick, or Sir Nicholas, is the Gryffindor House ghost who in life was sentenced to death by beheading after a teeth-straightening spell went awry on Lady Grieve. Unfortunately, the executioner's axe was blunt and Nick's head was still attached to his neck by a thin strip of skin after 45 chops. Harry becomes friends with Nick when he attends his "deathday" party (the 500th anniversary of the event) in a Hogwarts dungeon. Nick's death date (31 October 1492) has the distinction of having served as the basis for the entire chronology of the Harry Potter stories, until the timeline was confirmed by the headstone of James and Lily Potter in Harry Potter and the Deathly Hallows. His greatest wish is to become a member of the Headless Hunt, as mentioned in the second book. However, he is excluded due to the fact that he is not actually headless and would not be able to fully participate in the activities (such as Head Polo).

In Chamber of Secrets, Nick is a victim of the Basilisk that Ginny Weasley unleashes under the influence of Tom Riddle. The stare of the Basilisk is lethal to anyone who looks it directly in the eye. All of its living victims meet its gaze indirectly, either from a reflection or by seeing it through something else, and are only petrified rather than killed. Nick is the only one to look directly at the Basilisk, but he too is petrified since he is already dead.

The character appears again in Harry Potter and the Order of the Phoenix when Harry has been looking for comfort upon the death of Sirius Black, hoping he can see him later as a ghost. Nick explains that only witches and wizards who fear death and refuse to go on can become ghosts, dashing Harry's hope of communicating with Sirius. He appears briefly in Harry Potter and the Deathly Hallows, when Harry asks him to bring him to the Grey Lady.

The character is portrayed in the film series by John Cleese.

Hogwarts founders
Hogwarts was founded a millennium ago by "four of the greatest witches and wizards of the age": Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and Salazar Slytherin. The founders served as Hogwarts' first teachers, and each of the Hogwarts houses is named after one of the founders.

Godric Gryffindor
Godric Gryffindor hailed from a moor that is now known as Godric's Hollow, a small West Country village. Gryffindor is said to have praised courage, determination, and strength of heart above all other qualities. He also was the most in favour of allowing Muggle-borns into the school. He was initially a close friend of Salazar Slytherin, but over time their friendship deteriorated. "One of the four famous Founders of Hogwarts School of Witchcraft and Wizardry, Godric Gryffindor was the most accomplished dueller of his time, an enlightened fighter against Muggle-discrimination and the first owner of the celebrated Sorting Hat."

His known relics are a goblin-made sword adorned with rubies (the Goblins claim that Godric stole it from them, but Goblin notions of ownership are different from human views of ownership) and the Sorting Hat. The two items share a particular bond: whenever a "true Gryffindor" needs it, the Sword will allow itself to be pulled out of the hat. Godric's sword is goblin wrought silver, so it never needs cleaning and only takes in what strengthens it—when Harry kills a basilisk with it in the Chamber of Secrets it absorbed basilisk venom, making it suitable as a tool for destroying Voldemort's Horcruxes: Dumbledore uses it to destroy Gaunt's ring, Ron Weasley uses it to smash Slytherin's locket, and Neville Longbottom uses it to kill Nagini.

Helga Hufflepuff
Helga Hufflepuff came from a broad valley. The Sorting Hat describes her as "good Hufflepuff" or "sweet Hufflepuff". She favoured loyalty, honesty, and dedication. In Goblet of Fire, she is said to have considered "hard workers almost always most worthy of admission". Elsewhere, she is described as taking "all the rest" of the students after selection by her colleagues. She was a good friend of Rowena Ravenclaw; their friendship is used to emphasise the failed friendship between Godric Gryffindor and Salazar Slytherin.

"One of the four celebrated Founders of Hogwarts, Hufflepuff was particularly famous for her dexterity at food-related Charms. Many recipes traditionally served at Hogwarts feasts originated with Hufflepuff." Her wizard card, penned by Rowling, describes her as having "brought people from different walks of life together to help build Hogwarts", and being "loved for her charming ways". According to an interview between Rowling and staff from The Leaky Cauldron, Hufflepuff introduced house-elves to Hogwarts, where she offered them refuge. Both the famous wizard card and the illustration on Rowling's website depict her as a plump woman with red hair. Coincidentally, those two traits are commonly used to describe Molly Weasley.

One relic of Hufflepuff, a small golden cup, emblazoned with her symbol of a badger, is passed down to her distant descendant, Hepzibah Smith. This cup is stolen by Tom Riddle and made into a Horcrux.

Rowena Ravenclaw
 Rowena Ravenclaw was a witch noted for her cleverness and creativity, and was described by Xenophilius Lovegood as beautiful. The Sorting Hat introduces her as "Fair Ravenclaw, from glen", suggesting she was from Scotland. Ravenclaw devised the ever-changing floor plans and moving staircases in the Hogwarts castle, and coined the proverb "Wit beyond measure is man's greatest treasure." Ravenclaw is described by the Sorting Hat as having selected students according to intelligence and wisdom. "One of the four famous Founders of Hogwarts School of Witchcraft and Wizardry, Rowena Ravenclaw was the most brilliant witch of her time, though legend has it that a broken heart—cause unknown—contributed to her early demise." It is revealed in the Deathly Hallows that the broken heart contributing to her untimely death was most likely the loss of her daughter, Helena Ravenclaw, who is, in fact, the Ravenclaw House Ghost (nicknamed The Grey Lady), and the loss of her diadem, the very relic to which Ravenclaw's astounding wisdom was attributed.

In Harry Potter and the Deathly Hallows, Harry learns that an artefact of Ravenclaw's became a Horcrux: her lost diadem, which granted enhanced wisdom to its wearer. Her daughter, Helena Ravenclaw, had once run away with it to surpass her mother in terms of intelligence and wisdom and hid it in Albania, its whereabouts remaining unknown ever since. She, however, revealed its location to a young Tom Riddle, who proceeded to retrieve it and turn it into a Horcrux. In the original uncursed form, it is said to be able to imbue its wearer with great wisdom. Late in her life, Rowena, suffering from a terminal illness, sent for the Bloody Baron to find her daughter so she could see her one last time before she died. However, Helena refused to go with the Baron, and he killed her in a paroxysm of rage. Immediately overcome with guilt, he then took his own life.

Salazar Slytherin
Salazar Slytherin is described as power hungry by the Sorting Hat, and was known as "shrewd Slytherin from fen". One of the four celebrated Founders of Hogwarts School of Witchcraft and Wizardry, Salazar Slytherin was one of the first recorded Parselmouths, an accomplished Legilimens, and a notorious champion of pureblood supremacy." Slytherin is the only founder whose physical appearance is ever described in any detail; his statue in the Chamber of Secrets depicts a man "ancient and monkey-like, with a long thin beard that fell almost to the bottom of his sweeping robes." According to Dumbledore, the qualities that Slytherin prized in his handpicked students included his own rare ability to speak Parseltongue, resourcefulness, and determination. He also selected his students according to cunning, ambition, and blood purity. Slytherin's first name is a reference to the mid 20th century Portuguese dictator’s surname — Rowling’s stay in the country (where his presence is still felt long after the dictatorship era) inspired this name choice.

Slytherin's background is first discussed by Professor Binns in Harry Potter and the Chamber of Secrets (by Professor McGonagall in the film version): he describes the founding of the school and the schism which developed between Slytherin and the other founders, and he mentions that the castle was founded far from Muggles because, at that time, common people feared magic and persecuted suspected wizards and witches. Slytherin wanted magical learning restricted to all-magical families, as he believed Muggle-born students to be untrustworthy and he disliked teaching such students. According to ancient legend, Slytherin was responsible for the construction of the Chamber of Secrets. This chamber contained a magical creature, the Basilisk, susceptible to control by his Parselmouth descendants and left there to purge the school of all Muggle-borns. This occurred shortly before infighting among the four founders broke out and resulted in Slytherin's departure.

Slytherin owned a locket that became an heirloom for his last known line of descendants, the Gaunts; later it is turned into a Horcrux by Lord Voldemort, his last descendant, who shares his ancestor's obsession with maintaining blood purity in the wizard world, and lets that obsession consume him to make him the legendary outlaw and villain feared by all.