Amnesia is a medical disorder causing a deficit in one's memory, with different varieties affecting the long and short-term memory. It can be caused through a number of ways, such as brain damage or drugs, but often in media, it is often as a result of some physical trauma to the head.
- In Episode 0352 of Sesame Street, Cookie Monster trips on a stray rollerskate on the stoop of 123 Sesame Street. Landing on the pavement causes him to forget his entire identity and he spends much of the episode trying to find a new one (such as a bird, a grouch, or a mailbox). He ultimately gains his memory back by falling down the stoop in the same manner as before.
- Bert suffers a similar bout of amnesia in Episode 0612. Though the source of his memory loss is not acknowledged onscreen, his memory is temporarily restored after bumping into Mr. Snuffleupagus. A second bump causes him to lose his memory again, but an altercation with Cookie Monster at the episode's end brings his memory back once more.
- During the "A Frog Too Far" film in The Muppets Go to the Movies, Kermit the Frog, as a World War II pilot, develops amnesia as a result of a plane crash.
- The third act of The Muppets Take Manhattan focuses on Kermit losing his memory after being struck by a taxi cab. After the hospital is unable to cure his condition, he takes up a new identity as Philip Phil. A karate chop from Miss Piggy eventually returns him to normal.
- A bump on the head from a radish causes Boober Fraggle to think he's a Gorg in the Fraggle Rock episode, "Boober Gorg." He regains his memory after a stressful situation causes him to pass out.
- One of the symptoms of Canadian Snout Fever (established in The Jim Henson Hour episode "Fitness") is bouts of amnesia. Link Hogthrob believes he's contracted the infliction because he can't recall how he obtained the medical journal in which he discovers the symptoms (in actuality, it bonked him on the head).
- Big Bird suffers a similar affliction to amnesia in Episode 3396 of Sesame Street called "the memory flu" (named such because his memory "flew"). He is unable to remember the identity of himself or his friends, and even forgets what counting is. His condition is ultimately cured when he's presented with his favorite toy, Radar.
- In a Muppetism short, Miss Piggy karate chops Kermit, who crashes into various things off-screen. As he comes to, he's unable to recognize her and she takes the opportunity to claim she's his wife.
- Forgetful Jones, an individual blessed with perpetual memory loss