A ninja was a mercenary or agent operating in feudal Japan (1185–1333). Using covert methods, the function of a ninja was to engage in acts of espionage typically seen as dishonorable and beneath that of the samurai. Their tactics have slipped into legend and their depiction has often been exaggerated in modern media.
- On several occasions, the Muppet Babies dressed as ninjas, usually when playing characters from Teenage Mutant Ninja Turtles.
- Sam the Eagle acknowledges the viewer's steady stream of YouTube videos involving ninjas (and other things) to present a rendition of "American Woman".
- When the Muppets conspire to kidnap Jack Black in The Muppets, they dress as ninjas to conceal their activities.
- After witnessing a penguin perform martial arts, Kermit the Frog tells Miss Piggy that she could give up singing and become a ninja (referencing her penchant for delivering karate chops).
- Ninja Rogers is a tap-dancing ninja who uses his skills to play the drums in The Treasure of Peg-Leg Wilson.