Mark O'Brien
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).
Known for
Arrival 
Marriage Story 
Bad Times at the El Royale 
Nuremberg 
Ready or Not 
The Darkest Minds 
How It Ends 
Anon 
Blue Bayou 
Kin 
The Front Runner 
The Copenhagen Test 
Parallel 
How to Plan an Orgy in a Small Town 
Seven Veils 
State Like Sleep 
The Righteous 
Hammer 
Shadow of God 
End of Days, Inc. 
The Outer Threat 
Grown Up Movie Star 
The Four Horsemen