John Fleck played several guest roles on The Next Generation, Deep Space Nine, and Voyager before playing Silik, a major recurring character, on Enterprise. Silik was the Suliban responsible for plunging Jonathan Archer and the crew of the Enterprise NX-01 into the Temporal Cold War.

Initially, on TNG he first played Taibak, the Romulan agent charged with interrogating and training the brainwashed LaForge to be an unwitting assassin in "The Mind's Eye."