Acting • AGE 42
Mark O'Brien (born May 7th, 1984) is a Canadian actor and director. He is best known for playing the role of Des Courtney in Republic of Doyle (2010) and Tom Rendon in Halt and Catch Fire (2014).


The Outer Threat
2026

The Voices of Our Mother
William
2026

The Copenhagen Test
Edmund Cobb
2025

Nuremberg
Colonel John Amen
2025

The Memory Keeper
Elizeus Carrier
2025

Shadow of God
Mason Harper
2025

Seven Veils
Paul
2025

Topper
Topper
2025

The Sticky
Charlie
2024

61st Street
Officer Logan
2022

Blue Bayou
Ace
2021

The Righteous
Aaron Smith
2021

Your Honor
Father Jay
2020

Perry Mason
Thomas Milligan
2020

Hammer
Chris Davis
2019

Marriage Story
Carter Mitchum
2019

The Kelly Clarkson Show
Self
2019

Ready or Not
Alex
2019

City on a Hill
Jimmy Ryan
2019

Goalie
Terry Sawchuk
2019

State Like Sleep
Darren
2019

The Front Runner
Billy Shore
2018

Bad Times at the El Royale
Larsen Rogers
2018

Kin
Jake
2018

The Darkest Minds
Rob Meadows
2018

How It Ends
Jeremiah
2018

Anon
Cyrus Frear
2018

Parallel
Josh
2018

The Last Tycoon
Max Miner
2017

Arrival
Captain Marks
2016

Wanderer
Eric
2016

The Dark Stranger
Mark
2016

How to Plan an Orgy in a Small Town
Bruce Buck
2015

Killjoys
Grayson Hicks
2015

End of Days, Inc.
Jason
2015

Dennis
Dennis
2015

Halt and Catch Fire
Tom Rendon
2014

Hannibal
Randall Tier
2013

Beat Down
Michael
2012

Kathy
Director
2011

Snarbuckled
Jacob O'Higgins
2010

Grown Up Movie Star
Will
2010

Republic of Doyle
Des Courtney
2010

Warehouse 13
Jerry Hoffler
2009

Heartless Disappearance Into Labrador Seas
Charlie
2008

The One That Got Away
Tommy Palchek
2008

The Four Horsemen
Eric Rollins
2008

Little One