Beck is known predominantly for his roles as Swan in the action film The Warriors (1979), Sonny Malone in Xanadu (1980), Lieutenant Commander Dallas in Megaforce (1982), and Koda in The Triumphs of a Man Called Horse (1983). Beck also appeared in other movies such as Alcatraz: The Whole Shocking Story (1980, as Clarence Carnes), Warlords of the 21st Century (1982), The Last Ninja (1983), The Golden Seal (1983, as an evil poacher), Wes Craven's Chiller (1985, as a cryonically suspended sociopath), Gone to Texas (1986, as Jim Bowie), Forest Warrior (1996, starring Chuck Norris), and Jungle Book: Lost Treasure (1998).
Beck appeared as Hans Helms in the 1978 TV miniseries Holocaust, and also starred in a short-lived television series, Houston Knights (1987), in the role of Sgt. Levon Lundy. More recently, Beck starred in television shows JAG, Robin's Hoods, Walker Texas Ranger (in the episodes Flashpoint and Second Chance), In the Heat of the Night, and as the Mars-born terrorist-turned-cyborg assassin Abel Horn in Babylon 5 episode "Spider in the Web", and as Mr. Jones in the spinoff series Crusade (episode "The Well of Forever").
Beck has narrated numerous audiobooks of John Grisham's novels. He has also narrated Confederates in the Attic by Tony Horwitz; A Darkness More Than Light by Michael Connelly; State of the Union by David Callahan; and the unabridged version of Bill Clinton's My Life. He also reprised his role as Swan in 2005, lending his voice to the popular video game adaptation of The Warriors.