He is best known for starring as Herbert West in the H.P. Lovecraft adaptation Re-Animator  and portraying a number of characters in the Star Trek universe, most notably Brunt and the various Weyouns on Star Trek: Deep Space Nine, and Shran on Star Trek: Enterprise.

Combs has been a prominent figure within the horror genre through most of his career, acting in eight films directed by Re-Animator director Stuart Gordon such as From Beyond, The Pit and the Pendulum, and Castle Freak. Other horror film appearances include Necronomicon, Peter Jackson’s The Frighteners, I Still Know What You Did Last Summer, House on Haunted Hill, and Would You Rather. As a voice actor, he’s best known as the voice of Question on Justice League Unlimited and Ratchet on Transformers: Prime.