Ice King is the one of the rappers who appeared in Discord vs Ice King. Played by Zach Schroeder, Simon is the main character of Cartoon Network's Adventure Time created by Pendleton "Pen" Ward. He battled Discord.
The Ice King (formerly Simon Petrikov) is the former main antagonist of Adventure Time. His typical crime is 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 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, his unusual blue skin color, his protruded goblin-like nose, blank eyes, and stark-white beard. 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."
Nice King is the beardless alter ego of the Ice King, who appears in "Loyalty to the King." The reason for his existence was the Ice King's choosing to shave his beard, in hopes that it would make him more attractive to princesses after innumerable failed captures. When going out in public in his beardless form, a misinterpretation by Slime Princess when introducing himself ("a nice king," instead of "an ice king") ultimately leads to the princesses trying to court him. He also dubs Finn and Jake his loyal "Nice Knights," commanding them to interview his prospective princesses auditioning for a date.
In "The Eyes," Ice King spies on Finn and Jake, disguised as an odd-looking horse. It has a very "un-horse-like" face with ever-staring eyes and a protruding tongue. Its vacuous expression leads Jake to suspect it has a case of being "whacked-out with poo brain." Finn and Jake try various approaches in order to get rid of him. When Finn finally kicks it, Ice King pops out of the inflatable horse costume. According to the Frederator Blog, the design for this horse was inspired by Kate Beaton's Hark! A Vagrant comics, which features a similar Fat Pony character.
In "Still," The Ice King freezes Finn and Jake with "Freezing Potion A" so that they can bond. One of his bonding activities is better understanding each other's perspectives by dressing up like each other. He knots his robe so that it is the same length as a t-shirt and colors his feet black with a marker to make his clothes look like Finn's. He then wraps his beard around the top of his head and pulls two tufts out of the top to mimic Finn's hat. As the finishing touch, he creates a backpack out of ice to look like Finn's pack.
In "Princess Potluck," Ice King tries to get the Banana Guards to stop Princess Bubblegum's potluck. The Banana Guards say they hate him when he calls and introduces himself as Ice King. He calls again and says that he is Mr. Garamblington. He wears a hard hat to help him improve the personality he uses.