Svengali's Assistant

From Muppet Wiki

Svengali's Assistant is a pink, female monster who sings "You Do Something To Me" in episode 112 of The Muppet Show. During the song, Svengali transforms her into all sorts of different creatures, each with the same pink head. At the end of the number she transforms into an older-looking woman, who is voiced by Eren Ozker, and who expresses relief at being back to herself again.

She also appeared in the opening from seasons 2-5 and in "At the Dance" in episode 202.