Early Episodes:
* "Slumber Party Panic": Ice King's first appearance, he kidnaps Princess Bubblegum for a slumber party.
* "The Enchiridion!": Ice King receives the Enchiridion, which grants him a variety of powers.
* "Prisoners of Love": Ice King captures Finn and Jake, and Finn falls in love with him (accidentally).
* "The Duke": Ice King tries to marry Princess Bubblegum, who quickly rejects him.
* "Rainy Day Day": Ice King gets a new power to manipulate weather.
Episodes Focused on Ice King's Backstory:
* "I Remember You": A flashback episode showing Ice King's past as Simon Petrikov and his relationship with Marceline.
* "The Lich": Ice King battles the Lich, a powerful and evil entity.
* "Holly Jolly Secrets": Ice King faces a dark secret about his past.
* "Orgalorg": Ice King faces his past trauma and fights a giant space monster.
Episodes with Unique Ice King Moments:
* "The Real You": Ice King attempts to be a good role model for Finn and Jake.
* "Be More": Ice King struggles with his mental health and his desire to be better.
* "The Cooler": Ice King battles a giant, sentient cooler.
* "The Vault": Ice King helps Finn and Jake find a treasure.
* "The Hardest Thing": Ice King shows surprising emotional depth and helps Finn and Jake.
Episodes with a Strong Presence of Ice King:
* "Adventure Time with Finn and Jake": Ice King often appears in the opening theme song.
* "Adventure Time": Ice King is a recurring character throughout the series.
This list is far from comprehensive, and many other episodes feature Ice King in significant ways. He is a complex and fascinating character, often both comical and tragic, and his appearances throughout Adventure Time add depth and humor to the show.
If you're looking for more specific episodes that focus on Ice King's relationship with a particular character, his backstory, or his magical abilities, you can search online for "Adventure Time episodes featuring Ice King" or "Ice King Adventure Time" to find more detailed lists and resources.