He appeared in many Canadian television productions in the 1990s and 2000s. He played Michael, Nick Eliot's boss in The Crush. He played Father Mac in 22 episodes of the television series Hope Island, and Max Asher in 11 episodes of MythQuest. He also played the recurring character Ian MacLeod, the father of Duncan MacLeod in Highlander: The Series, Father Perry in Mysterious Ways and Merlin in the Stargate television franchise. In 2007, he was nominated for a Leo Award for "Best Supporting Performance by a Male in a Dramatic Series" in the Stargate SG-1 episode "The Quest (Part 2)". He also played Mr March in Little Women.
|1989||We're No Angels||Blacksmith|
|1994||Little Women||Mr. March|
|2001||Spy Game||MI6 Agent Digby 'Digger' Gibson|
|2006||Night at the Museum||Politician|
|2007||Christmas in Wonderland ||Santa / Mr. Nicholas / Mall Ghost / Kristopher Kringle / Old Man With Walker|
|1992||Bill and Ted's Excellent Adventures||Uther Pendragon||Episode: "Nail the Conquering Hero"|
|1996||The Angel of Pennsylvania Avenue||Handy Andy||Television movie|
|1999||Master Keaton||Detective Rupert / Oscar Hammer (voices)||English version|
Credited as Mathew Walker
Episodes: "The Island of Cowards" and "The Forbidden Fruit"
|1999–2000||Hope Island||Father Mac||22 episodes|
|2001||MythQuest||Max Asher||9 episodes|
|2005–2007||Stargate SG-1||Merlin||4 episodes|
|2007||Smallville||Dr. Hudson||Episode: "Labyrinth"|
- "Comparing the Casts of Little Women, Then & Now". E! News. 20 December 2019. Retrieved 2020-03-11.
- Campe, Shannon (2019-12-23). "The Christmas Spirit of the 1994 "Little Women"". The Spool. Retrieved 2020-03-11.
- Warnke, Melissa Batchelor (2018-09-21). "Christian Bale in 'Little Women' Taught Me It's Hot to Be Smart". Vice. Retrieved 2020-03-11.