Cake The Cat is the gender- (and species-) swapped version of Jake The Dog in the Ice King's self-written fan-fictions, created by Adventure Time character designer Natasha Allegri. She features in the episodes "Fionna and Cake," "Bad Little Boy," "The Prince Who Wanted Everything," and "Five Short Tables" and is mentioned by the Ice King in "King Worm" and "Mystery Dungeon."

Cake travels with Fionna The Human, and Lord Monochromicorn is her boyfriend. She has Stretchy Powers and can morph her body just like Jake. As a cat, she also possesses the ability to see in the dark. The fur on her tail stands on the end (or "frizzes out") when there is danger around or when she gets excited (e.g., when Lord Monochromicorn speaks to her).

In the spin-off series "Fionna & Cake" it's revealed the Fionna Campbell and Cake the Cat are in fact real people. Specifically, Prismo the Wishmaster wrote the original Fionna & Cake Fan-Fiction and broke cosmic entity law to grant himself a wish to bring his fanfiction to life. This resulted in the creation of a secret unauthorized universe within the multiverse. In order to keep it hidden, Prismo shrunk the universe and uploaded it into the brain of Ice King where nobody would ever find it. This is where, Ice King got the idea for Fionna & Cake and his obsession with trying to bring the characters in his fanfiction to life. Following the Adventure Time Series Finale "Come Along With Me", the magic of the Ice Crown was digested by GOLB reverting Ice King to the mortal Simon Petrikov.This also resulted in the digestion of the magic within Fionna & Cake's Universe, causing everyone to become normal humans and animals with Cake becoming a normal cat incapable of speech.