The following stars appeared on the show in order of appearance

George Hamilton, Morgan Fairchild (five), Peter Bogdanovich, Marissa Ribisi, Zsa Zsa Gabor, Elliott Gould, Kevin Sorbo, Wendie Malick, Tracy Scoggins, Paula Abdul, Phyllis Diller, Isabel Sanford, Marsha Warfield, Candace Cameron Bure, Jane Kaczmarek (five), Dinah Manoff, Danny Masterson (nine), Roseanne (voice), Shari Lewis, Arthel Neville, Seth Green, William Forsythe, paula Poundstone (two), and Bruno Campos, Joyce DeWitt, Erik Estrada (two), Audra Lindley, Denver Pyle, and Joan Van Ark.

I am actually watching "Cybill" on Oxygen as we speak and Tony Bennet was on, and I did not see that name in the list, so...um, well, he was on! :happyface

Robert Stack was also on an eppie and i didn't see his name in their either! And don't 4get Cybill's daughter 'Clementine' was on a few eppies as well!

Feen

Paula Poundstone was on several episodes.
Ted Shackelford (knots landing) was on an episode.

Also:

Add Jonathan Frakes from Star Trek: NExt Generation. Very cool!!!

Good eye on the Joyce DeWitt; I noticed she did NOT get credited on Oyxgen for her comments about the Psychic Pals network. Very cool of Joyce to do a cameo, considering her fame!

Alice Ghostley and Phyliss Diller

Here's Joyce in "The Odd Couples":

^ I missed that one with Joyce DeWitt, hope it gets repeated.


Also Burt Reynolds, Kenny Rogers & Chad Everett have made guest appearances on the show.