Gnome Knight

The Gnome Knight appears in the episode "The Pods". After Finn and Jake find him, he tells them he was a gnome knight who was transformed into a frog. He has been guarding three magical beans because one of them is evil, and he must prevent them from ever being planted. However, he is now on the verge of death. Finn agrees to take over his quest and takes the beans, which causes him to revert into a gnome. When Jake says he doesn't want the quest, the gnome says "Nope, too late." Then he promptly dies and disintegrates into dust, leaving only his helmet and dust.