Alfredo and Hildegard

From Muppet Wiki

Alfredo and Hildegard, the Mop Dancers, performed on episode 309 of The Muppet Show when Kermit sent them onstage to sweep up the broken plates from Miss Piggy's opening number "Never on Sunday."

Alfredo is the feminine-looking, gray-skinned Whatnot, and Hildegard is the masculine-looking, green-skinned Whatnot, which leads to confusion when Kermit wishes "Hildegard" good luck and she snaps back, "I'm Alfredo!"

Alfredo was performed by Dave Goelz.