The Ice King

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 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. Despite looking fat in his garments, Ice King has lean trained body due to him working out on a regular basis.