There are so many Adventure Time characters, that we had to divide them all up into four sections.
Main Characters: Click to Expand Finn the Human, Jake the Dog, Princess Bubblegum, Lady Rainicorn, BMO, Lumpy Space Princess, Marceline the Vampire Queen, The Ice King, The Lich, Flame Princess
Secondary Characters: Click To Expand Tree Trunks, Earl of Lemongrab, Gunter, Peppermint Butler, Cinnamon Bun, Shelby, Death, NEPTR, Billy, The Magic Man.
Minor Characters: Click to Expand Susan Strong, The Snail, Me-Mow, Ash, Lemongrab 2, Lemonjon, Lemon Children, Prismo, Big Destiny, Duke of Nuts, Ricardio, Hunson Abadeer, Flambo, Flame King, Abraham Lincoln, Minor Princesses, Candy People, Cuber, James Baxter, Island Lady, Jake Jr., The MO Factory, Maja, King Worm, Scorcher, Choose Goose, The Ancient Sleeping Magi of Life Giving, Shoko, Betty, Bella Noche, Johnny, Phlannel Boxingday, The Grass Sword, Canyon, Peace Master, Dad The Human
Fionna and Cake Characters: Click to Expand Fionna, Cake, Prince Gumball, Lord Monochromicorn, Marshall Lee, Ice Queen. Also Ice King, Gunter, Lumpy Space Prince, Lady Lemongrabs, and BMO.