Ninjas

The Ninjas make their first appearance in The Adventure Time Original Short, where they steal an Old Man's diamonds in broad daylight and an open field. They have not been seen in the series so far. However, they have been seen in the in the second level of the game Righteous Quest, and on the last level of Righteous Quest 2, before the fight with Marceline. It is also known that Finn, Jake, and the Ice King are into ninjas, as shown in The Chamber of Frozen Blades. However, the Ice King is more into it, owning several ninja artifacts and even having a secret ninja room.