He has performed extensively in theatres across Canada from Victoria, BC to St. John's, Newfoundland. He has played key roles as Malcolm Lowry in the Vancouver Playhouse production of Goodnight Disgrace, James Tyrone Jr. in the Neptune Theatre production of Moon for the Misbegotten and Nick in the National Theatre production of Who's Afraid of Virginia Wolfe. He also performed for two seasons at Vancouver's Bard on the Beach playing Edmund in King Lear and Claudius in Hamlet. He also played Scrooge in Carousel Theatre's 1999 A Christmas Carol and has toured Canada, the United States, Europe and Africa with The Great Mozart Hunt.
Halder has appeared as a guest star in Highlander: The Series, Millennium, and Hope Island as well as playing roles in The X-Files, The Outer Limits (1995), Dead Man's Gun and Poltergeist. He also has the role of recurring Stargate SG-1 character Cronus. He is currently involved in voice-work for cartoons, where he usually plays the role of an eccentric doctor/professor, a kindly older man/mentor, or a hard and malicious man. He has also taught stage fight combat at the Canadian National Theatre school in Montreal, and has choreographed numerous "safe" fight scenes for both stage and camera.