The Cameos of Star Trek
A bunch of famous actors and actresses have made appearances in the Star Trek films and episodes. To name a few: Kim Cattrall, Tom Hardy, Kirstie Alley, Jason Alexander, Tom Bergeron, Stephen Hawking, Kelsey Grammer, Christopher Plummer, The Rock, Iman, Lee Meriwether, Joan Collins, Mick Fleetwood, Ashley Judd, Famke Janssen, Mae Jemison, and Tom Morello, and King Abdullah II of Jordan,
Source: Variety
Other than the franchises’ cameos, Leonard Nimoy and William Shatner are the only two actors to appear in every episode of the original Star Trek series.