Trolls

From Muppet Wiki

Trolls are full-bodied Muppets who appear in dance numbers on The Muppet Show.

The red-haired Troll first appeared as Rico in the "Copacabana" number in episode 414 opposite Liza Minnelli as Lola and a Mutation as Tony. He was joined by two more Trolls, one green-haired and one gray, in a dance number in episode 416. The three appeared as pirates in episode 507.