The Aristocrats

From Muppet Wiki

The Aristocrats, as they're called in Monster Hits, are the group of monsters who sang "Fur" on Sesame Street.

The lead singer is Stuie Monster, and the back-up singers are a fat blue Anything Monster, Maurice Monster, and a lavender Anything Muppet covered in fur.

These three monsters also appear in the songs Frazzle (where the fat blue monster resembled Little Chrissy) and I Want a Monster to Be My Friend.