Besides Adam Sandler, Angela Bassett made some guest
appearances on The Cosby Show. Also, Michelle Thomas, who played
Myra on Family Matters, played Theo's girlfriend Justine, and Lisa
Vidal and Lela Rochon-Fuqua(both of The Division) made cameos.

And don't forget the I Spy reunion with Robert Culp!

John Ritter was a special guest star in the 1991 season.

The dancer Danny Kay, when Peter had to go to the dentist.
Sammy Davis Jr couldn't read

His former I SPY co-star, Robert Culp, appeared in at least one episode.

Robin Givens

Dizzy Gillespie
Alicia Keys
Sinbad
Stacy Dash
Tzi Ma - "the chinese guy that abducted Jack Bauer on "24"