|Vehicles and/or Gadgets||None|
|Occupation||Mount Cragdor Gatekeeper|
|Residence||Land of Ooo|
Key-per, or Gate Key-per, makes his first appearance in Adventure Time in the episode "The Enchiridion!" His key-shaped hat is, in fact, the key that opens the gate to Mount Cragdor. (This means that the Key-per himself must be literally inserted into the lock). After Finn uses him to open the gate, the Key-per asks how Finn figured it out. Finn replies, "I just thought you'd look cute stuffed in that lock." The Key-per affirms Finn's choice, saying this is the answer to the riddle. He also says that this is the same conclusion that previous adventurers reached to enter, but Finn and Jake are already leaving him behind. Key-per is able to talk very fast, as is Booko in "The Lich," and his speeches are usually difficult to understand because of how quickly he says the words. He is the gate keeper to the pathway of The Enchiridion. After defeating the Dark Magician, Finn, in his rage, sees Key-per in red, devilish pajamas, mistakes him for another trial, and punches him in the stomach. The Key-per, lying hurt on the ground innocently, explains that they are his pajamas. He then makes spaghetti for the picnic after the quest along with Mannish Man, Finn, Jake, and a couple of Old Ladies.
- In the episode "The Enchiridion", he was voiced by John Moschitta Jr. who reprises his role in the game.
- In the Spanish dub, he's known as "Llavero" (English translation meaning "Keychain").