Mark O'Brien (born May 7, 1984) is a Canadian actor and director. He is best known for playing the role of Des Courtney in Republic of Doyle and Tom Rendon in Halt and Catch Fire.
The Voices of Our Mother
• Director
The Righteous
2021 • Director
Wanderer
2015 • Director
The Kelly Clarkson Show
2019 -
Shadow of God
• Mason Harper
Nuremberg
• Col. John Amen
Seven Veils
2023 • Paul
Perry Mason
2020 - 2023 • Thomas Milligan
Your Honor
2020 - 2023 • Father Jay
City on a Hill
2019 - 2022 • Jimmy Ryan
61st Street
2022 - • Officer Logan
Blue Bayou
2021 • Ace
2021 • Aaron Smith
Hammer
2019 • Chris Davis
Marriage Story
2019 • Carter Mitchum
Killjoys
2015 - 2019 • Grayson Hicks
Ready or Not
2019 • Alex Le Domas
Goalie
2019 • Terry Sawchuk
State Like Sleep
2018 • Darren
The Front Runner
2018 • Billy Shore
Bad Times at the El Royale
2018 • Larsen Rogers
Kin
2018 • Jake
The Darkest Minds
2018 • Rob Meadows
How It Ends
2018 • Jeremiah
Anon
2018 • Cyrus Frear
Parallel
2018 • Josh
Halt and Catch Fire
2014 - 2017 • Tom Rendon
The Last Tycoon
2016 - 2017 • Max Miner
Arrival
2016 • Captain Marks
The Dark Stranger
2015 • Mark
How to Plan an Orgy in a Small Town
2015 • Bruce Buck
Hannibal
2013 - 2015 • Randall Tier
End of Days, Inc.
2015 • Jason
Republic of Doyle
2010 - 2014 • Des Courtney
Warehouse 13
2009 - 2014 • Jerry Hoffler
Beat Down
2012 • Michael
Snarbuckled
2010 • Jacob O'Higgins
Grown Up Movie Star
2009 • Will
Heartless Disappearance Into Labrador Seas
2008 • Charlie
2019 • Executive Producer