The Frazzletones

From Muppet Wiki

The Frazzletones, a backup singing group of monsters, appeared on Sesame Street in 1975 singing the song "Frazzle" with Frazzle himself. The song was released on the album The Sesame Street Monsters!.

Maurice Monster was one of the monsters. The dark-blue Frazzletone monster was made out of the Harvey Monster puppet with a yellow wig added. The Frazzletones were performed by Christopher Cerf, Richard Hunt, and Jerry Nelson.