Ice King

Ice King, formerly Simon Petrikov, is the former main antagonist and now supporting character of Adventure Time. His typical crime was to kidnap a princess and force her to marry him, which Finn and Jake 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.