The Riddle Master is one of Jake's many imaginary monsters in the episode "Rainy Day Daydream." The riddles are controlled by Jake. If someone does not answer his riddle correctly, the penalty is death by poisonous snakes. He was blocking a door on the bridge that Finn and Jake needed to cross to gain access to Jake's Imagination machine, and demanded they answer his riddle. His riddle was: "Tell me, voyager, what is simple, and yet also a riddle?" Finn responds by stating "Man, that riddle sucks." The Riddle Master then states, "That is the wrong answer! The penalty is death...by snakes!" The Riddle Master was apparently "killed" when Finn kicked a missile at him, releasing the imaginary snakes.
- In the Season 1 DVD Commentary for the animatic, Pendleton Ward states there is no answer to the riddle.