Frasier himself, Kelsey Grammer, was in an episode of “Star Trek: The Next Generation” as the captain of the ship stuck in a time loop and on a collision course with the Enterprise.
Kelsey Grammer’s TV wife Lilith, played by Bebe Neuwirth, also was on “The Next Generation.” She was an alien nurse who vowed to help Commander Riker break out of confinement in exchange for sexual favors.
Another “Cheers” star, Kirstie Alley, was Saavik in “Star Trek II: The Wrath of Khan.”
Jeffrey Dean Morgan
Jeffrey Dean Morgan knows how to play the villain. Before he was the baseball bat swinging Negan in “The Walking Dead,” Morgan was a Xindi-Reptillian tasked with eliminating Earth in “Star Trek: Enterprise.
Iggy Pop, the punk legend who made “The Passenger,” “Search and Destroy” and more, was in “Star Trek: Deep Space 9” as Yelgrun, a Vorta negotiator.
Before Famke Janssen and Patrick Stewart would be together in “X-Men” the actress appeared in an episode of “Star Trek: The Next Generation” where she seduced Stewart’s, Jean-Luc Picard.
Just with the number of references in his shows “Family Guy,” “American Dad” and films “Ted” and “Ted 2,” it’s clear that Seth Macfarlane is a true Trekkie. Happily, Macfarlane was able to be in a couple of episodes of “Star Trek: Enterprise” as a Starfleet engineer.
Andy Dick of “NewsRadio” played in an episode of “Star Trek” as a holographic ship doctor.
“Heat” and “Divergent” actress Ashley Judd was in two episodes of “Star Trek: The Next Generation.” Also, Judd had her first on-screen kiss with Wil Wheaton’s Wesley Crusher.
Before Terry O’Quinn was on the island in “Lost” as John Locke, he was an admiral in “Star Trek: The Next Generation” as well as a friend of William Riker.