Ice King

The Ice King (voiced by Tom Kenny) is the central antagonist (often unintentionally) of Adventure Time, and is 1,043 years old.

Character
The Ice King frequently kidnaps princesses throughout Ooo to forcefully marry them, Princess Bubblegum being his usual target. His ice-based magic abilities come from a magical crown he wears, which directly causes his insanity. Though defined as completely crazy by many, the Ice King is actually lonely and misunderstood, having a generally benevolent relationship with the penguins of his realm. Despite rarely meaning harm, the Ice King is still potentially very dangerous due to his power and his unstable mind. Furthermore, he is secretly envious of Finn and Jake for being such good friends. Finn and Jake learned during the events of "Holly Jolly Secrets" that the Ice King was originally a human antiquarian named Simon Petrikov who bought his crown from a dock worker in northern Scandinavia, predating the Mushroom War. Wearing the crown, Petrikov began to lose both his mind and then his fiancée Betty; this explains his subconscious need for princesses. He soon began deteriorating in both mind and body over the years into his current state. Sometime before the Mushroom War he discovered the Enchiridon; 996 years before the events of the series he met, befriended, and took care of young Marceline. Eventually, he realized that his deteriorating mind and behavior would possibly become a threat to young Marceline. Thus, he wrote a letter to Marceline, describing why he could not help her anymore and imploring her to forgive him for whatever wrong he might do with the crown possessing him.

Powers
The Ice King wields a variety of magic mainly dealing with ice and snow. He can freeze things with icy lightning bolts, and can summon blizzards even in summer, enough to bury most of Finn and Jake's Tree Fort. He has been seen forming various projectiles out of ice. He can also animate beings of ice and snow, like the Ice-o-pede and snowman soldiers. His beard, parting and flapping like a pair of wings, allows him to fly. Lastly, he can perceive the Spirit Realm with his "Wizard Eyes". In his insanity, his plans often only make sense to him alone, making it hard to predict what he will do. In the episode "Mystery Dungeon" it is revealed that his powers don't work in hot places.