Character: ice king
Ice King (real name Simon Petrikov) is a major character conceived, but no longer acting as, the main antagonist of Adventure Time. His typical crime would be to kidnap a princess and force her to marry him, which Finn and Jake would foil every time. As his name suggests, Ice King is also his title, announcing himself as King of Ice; the ruler of the Ice Kingdom. His magical abilities are contained in, and can be controlled with, his crown, and he is therefore powerless without it. His crown is also the cause of his loss of sanity and transformation into a wizard, though not a very good one, shown when Princess Bubblegum is possessed by the Lich, she says "The Ice Wizard is a weak fool." Due to his poor mental health, he is often misunderstood, making him a tragic hero in some cases, such as in "Mortal Recoil" and "I Remember You." Some time before the Mushroom War, he discovered the Enchiridion and bought the crown during his various expeditions around the world. Ice King's gender-swapped character is the Ice Queen, as seen in "Fionna and Cake."
This tag implicates adventure_time (learn more).