Dwayne “The Rock” Johnson. Tom Hardy. Kelsey Grammer.

They’re some of the biggest names in film and television, and all have something in common: guest starring roles on “Star Trek.”

Some characters weren’t too much of a stretch: Johnson played an alien gladiator. But do you recognize a slim Tom Hardy as a Romulan warlord? And you won’t believe the number of celebrities who have played the ridge-headed Klingons: Christopher Plummer, Christopher Lloyd, and John Tesh to name a few.

Plenty of actresses have also ventured where “no one (previously “no man”) has gone before.”

A young Kirsten Dunst appeared on “Star Trek: The Next Generation,” as did Ashley Judd and Teri Hatcher. And long before she appeared opposite Patrick Stewart in the “X-Men” movies, Famke Janssen played his love interest on the show.

As the sci-fi franchise celebrates its 50th anniversary on September 8, we look back at the various celebrities who have had cameos.

Which “Sex and the City” actress donned a Starfleet uniform? Which rockers have rocked alien prosthetics? Find out by clicking on the gallery below.

Stars You Didn’t Know Were In ‘Star Trek’