With a career spanning five decades beginning in the 1970s in television and movies, he is perhaps best known for his starring role as Detective Matthew Sikes in the television series Alien Nation (1989–1990) and five subsequent Alien Nation television films (1994–1997), as well as his work in the Star Trek franchise, most notably the recurring role of Soval, the Vulcan ambassador to Earth in Star Trek: Enterprise.

One of his earliest roles was in the 1980 CBS miniseries Scruples, based on the Judith Krantz novel starring Lindsay Wagner.

He also guest-starred on Star Trek: Voyager (1995) once, playing Ocampan community leader Tanis in the second-season episode "Cold Fire".

In 2015, Graham reprised his role as Ambassador Soval, in the fan film Star Trek: Axanar.

[4] Graham's film appearances include Hardcore, The Hollywood Knights, All the Right Moves, The Arrogant, The Last Warrior, Robot Jox, Running Woman and Siren.