| Year | Title | Role | Notes |
| 1991 | Police Rescue | Sergeant | Episode: "Hostage" |
| 1993 | Time Trax | Mr. Michaels | Episode: "One on One" |
| 1997 | Big Sky | Graham James | Episode: "Future Past and Present" |
| 1998 | Water Rats | Dr. Harry | Episode: "Epiphany" |
| 1998–2004 | All Saints | Dr. John Madsen | 32 episodes |
| 1999 | Airtight | Sorrentino | Television film |
| 2000 | Tales of the South Seas | Christian Ambrose | Episode: "Trent in Love" |
| 2000 | Virtual Nightmare | Dad | Television film |
| 2001 | Sir Arthur Conan Doyle's The Lost World | Inspector Robert Anderson | Episode: "The Knife" |
| 2001 | The Bill | Commander Warren | Episode: "Beech on the Run" |
| 2001–2006 | Home and Away | Dr. Helpman | 9 episodes |
| 2002 | Young Lions | Adam Gallagher | 4 episodes |
| 2002 | Stingers | Michael Kranz | Episode: "Disgraceful Conduct" |
| 2002 | The Outsider | Fergus Hunter | Television film |
| 2004 | The Mystery of Natalie Wood | Irving Pichel | Television film |
| 2002 | Superfire [it] | Paul Baylis | Television film |
| 2006 | Stargate SG-1 | Meurik | Episode: "Camelot" |
| 2007 | Journeyman | Wine Connoisseur | Episode: "Winterland" |
| 2007 | The Unit | The CEO | Episode: "Pandemonium – Part 2" |
| 2007 | 24 | Anatoly Markov | 3 episodes |
| 2007 | Pirate Islands: The Lost Treasure of Fiji | Blackheart | 13 episodes |
| 2008–2013 | Fringe | Walter Bishop / Walternate | 100 episodesCritics' Choice Television Award for Best Supporting Actor in a Drama SeriesSaturn Award for Best Supporting Actor on TelevisionNominated—Critics' Choice Television Award for Best Supporting Actor in a Drama SeriesNominated—Satellite Award for Best Supporting Actor – Series, Miniseries or Television Film (2008–09)Nominated—Saturn Award for Best Supporting Actor on Television (2010, 2012–13) |
| 2011–2012 | Dark Matters: Twisted But True | Himself | 16 episodes |
| 2011 | Transformers: Prime | Unicron | Voice, 3 episodes |
| 2013 | The Good Wife | Matthew Ashbaugh | 2 episodes |
| 2013 | Transformers Prime Beast Hunters: Predacons Rising | Unicron | Voice, television film |
| 2013–2017 | Sleepy Hollow | Henry Parrish | 22 episodes |
| 2013 | Miss Fisher's Murder Mysteries | Edward Stanley | Episode: "Murder Under The Mistletoe" |
| 2014 | Rake | Clayton Post | 2 episodes |
| 2014 | Devil's Playground | Bishop McNally | 6 episodes |
| 2015 | Forever | Aubrey Griffin | Episode: "The Last Death of Henry Morgan" |
| 2015–2019 | Elementary | Morland Holmes | 16 episodes |
| 2017–2018 | Legends of Tomorrow | Mallus, himself | 7 episodes |
| 2017–2018 | Salvation | Nicholas Tanz | 7 episodes |
| 2017 | The Librarians | Monsignor Vega | Episode: "And the Dark Secret", season 4 |
| 2018 | The Blacklist | Raleigh Sinclair III | 2 episodes |
| 2019 | The Resident | Elliot Festervan | Episode: "Broker and Broker" |
| 2020 | Hunters | Frederic Hauser | Episode: "The Pious Thieves" |
| 2020 | The Boys | Sam Butcher | Episode: "Butcher, Baker, Candlestick Maker" |
| 2021 | Debris | Otto | Episode: "Celestial Body" |
| 2021–2024 | Star Trek: Prodigy | The Diviner/Ilthuran | Voice; 28 episodes |
| 2021 | Cowboy Bebop | Caliban | 3 episodes |
| 2023 | Totally Completely Fine | Wilkinson | 3 episodes |
| 2023 | Fired on Mars | Falco | Voice; episode: "Marsiversary" |
| 2024 | Twilight of the Gods | Odin | Voice role |
| 2025 | Severance | Fields | Season 2 |
