From Muppet Wiki

Professor Gary Gill travels around the country selling the letter G. He shows up on Sesame Street with his two assistants in Episode 4076 to help Baby Bear improve his growl.

He is a spoof of Professor Harold Hill from the Broadway musical The Music Man, and the song he sings is a parody of "Ya Got Trouble."

Facts

• The Guy Smiley puppet is used for Gary. While it is an Orange Gold Anything Muppet, the Guy Smiley variation of the puppet has moving eyebrows (as evident by the small pegs behind them, visible in close-ups).