Princeton, a recently graduated English major and main character in the story along with Kate.

Kate Monster, a kindergarten teaching assistant(to Mrs. T) who wishes to create a school for monsters
Rod, a Republican banker who is secretly gay. Parody of Bert.

Nicky, Rod's roommate, a lazy slacker who has a tendency to mooch off Rod; Parody of Ernie.

Trekkie Monster, who spends his time on the internet looking at porn; Parody of Cookie Monster.

Lucy the Slut, a nightclub singer who is as slutty as her name suggests.

Gary Coleman, the former star of Diff'rent Strokes, is now the handyman of Avenue Q; a non-puppet character played by a female on Broadway, but a male in the West End
Brian, a down-on-his-luck 32-year-old who has trouble finding employment and dreams of being a stand-up comedian. Engaged to Christmas Eve. A non-puppet character.
Christmas Eve, a Japanese immigrant and Brian's fiancée. She is a therapist who has no clients; a non-puppet character.

Other Characters

Mrs. Thistletwat or Lavinia, a Kindergarten teacher

The Bad Idea Bears, the two adorable and sinister bears who can convince anyone to do something bad in the most adorable way.

The Newcomer, another new college graduate with a B.A in English, he wants to rent Christmas Eve and Brian's apartment but is put off by Princeton .

Ricky, the new boyfriend that Nicky has found for Rod on the internet. He looks exactly like Nicky but more muscualar which may explain the similariteies in their names.