From Muppet Wiki

Gillis Fraggle is a lavender Fraggle with green hair. He wears a black jacket and a pair of half-moon glasses.

Gillis is the resident musician of Fraggle Rock, but unlike the Minstrels, he lives in the Rock full-time. In "The Secret Society of Poobahs," Gillis was the Beggler-Beg of the Poobahs. His first appearance was in "Uncle Matt Comes Home."

Gillis' name is a reference to Fraggle Rock music arranger Don Gillis.