The Two-Headed Monster is, as the name implies, a monster with two heads. He speaks gibberish that resembles baby talk, and many of his skits have to do with either cooperation or sounding out parts of words that suddenly show up. Skits with the Two-Headed Monster usually take place with the monster behind a brick wall, and in at least one instance, with his mother.
The creation of this monster was inspired by performers Jerry Nelson and Richard Hunt playing around on the set one day, saying that they were a monster with two heads.[1] While right-handed performers use their right hands to perform the heads of characters and their left to perform left hands, whoever performs the left half of the monster performs the head with the left hand, and the right hand with their right hand.[2]
Although the heads don't normally go by names, they have been identified on occasion. In a Sesame Street sketch, Olivia reads a story to the Count about cooperation. It stars the Two-Headed Monster named Horn and Hardart. (SSvideo) In The Sesame Street Treasury Volume 13, the pair are featured in a photo answering phones. Their phones are labeled "Frank N." and "Stein" (Frankenstein).
From 2003 to 2006, the Two-Headed Monster made an appearance in each "Journey to Ernie" segment, with Big Bird asking both heads if they'd seen Ernie, and the monster pointing in both directions.
The question of whether the monster is a singular being or not has led to semantic confusion, typified by this exchange between Bert and Ernie in A Muppet Family Christmas:
Bert:Now, who let the Two-Headed Monster be Santa Claus?Ernie:Yeah, but, Bert, he said he'd never been in a play before... I mean they said it... um... both of him said it.