Actually, DogLion Beast is correct (it's just two words).
TMS:
#33 Madeline Kahn (debut- beautiful day sketch)
#35 Dom DeLuise (animal shelter sketch)
#41 Julie Andrews (closing # "Whenever I Feel Afraid")
#48 Cloris Leachman (closing #/sketch "Just in Time")
#55 Alice Cooper (closing # "School's Out")
#63 Lesley Ann Warren (Beauty and the Beast ballet; also goodnights)
#83 Lola Falana (Lola's first #, "He's the Greatest Dancer")
#93 Doug Henning (closing illusion)
The Muppet Movie- closing
The Muppets Go Hollywood- "Hooray for Hollywood" #; conga line
The Great Muppet Caper- "Hey, a Movie" (I think)
The Cosby Show- episode "Cliff's Nightmare"
Muppets Tonight:
Sandra Bullock- nets Mr. Poodlepants at the beginning; cameos in psychiatrist sketch w/Sandra & Kermit
Paula Abdul- sings & dances in "Opposites Attract"
Those are all the ones I know of.
David "Gorgon Heap" Ebersole