There has been a revolving door of "Sesame Street" characters since the revolutionary 1969 debut of this popular television show. Some "Sesame Street" characters have been around since the show's origins. Others appeared later.

Forgetful Jones. Forgetful Jones is a cowboy with a bad memory, who received his name because he always forgets things. He was a regular feature on "Sesame Street" throughout the entire span of the 1980s.

Lefty the Salesman. Frank Oz originally performed this trenchcoat wearing character in the first season of "Sesame Street". Lefty speaks in a whispery voice while trying to sell his wares to Ernie. The merchandise includes letters of the alphabet, invisible icecream cones and drawings of elephants. Lefty is a member of a crime ring that engages in alphabetic letter trafficking and other shady activities. One of lefty's more famous sketches is "Would You Like to Buy an O" in which he assures Ernie that "it will only cost a nickel."

Ernie. Ernie is the playful and fun loving character who loves to play jokes on his boring roommate, Bert. When he is not with Bert, he's usually being propositioned by back alley salesmen with trenchcoats or playing with his rubber ducky in the bathtub. 

Bert. Bert is the roommate of Ernie. Bert has a lot of ecclectic interests such as pigeons, paperclips and oatmeal. Bert's civic mindedness is revealed in his active membership in the W Lover's Club. Bert is often the unsuspecting victim of his roommate's practical jokes and games that get out of hand. Jim Henson performed the Ernie character before his death. 

Count Von Count. The Count looks like a frightening vampire with his fangs and cape. However, this "Sesame Street" character is quite friendly. The Count loves to count things really loudly. His counting sessions usually culminate with thunder and lightning. The Count spent the night at Ernie and Bert's apartment one time when Ernie was out of town. A bad case of insomnia had him annoying Bert after he took Bert's suggestion to count sheep as a sleep aid. 

The Martians. Two martian characters frequently appear on "Sesame Street" to discover such items as grandfather clocks, telephones and radios. They are characterized by tentacles, antennae and their catch phrase: "Yip yip yip yip yip yip yip yip. Uh huh. Uh huh." Their book of strange devices usually reveals to them the identity of the various objects these "Sesame Street" characters are inspecting. In one episode, they even land on Old McDonald's farm and make "Sesame Street News".