Mark O'Brien

Actor. Born 7 May 1984 in St. Johns, Newfoundland, Canada.

Titles on Fi1m

Average Fi1m score

Born

7 May 1984, St. Johns, Newfoundland, Canada

Active

2016–2019

Biography

Mark O'Brien is a Canadian actor and director. He was born on 7 May 1984 in St. John's, Newfoundland, and holds a Bachelor of Arts in English from Memorial University of Newfoundland.

He is best known for his role as Des Courtney in the television series Republic of Doyle (2010–2014) and as Tom Rendon in Halt and Catch Fire (2015–2016). His film credits include Captain Marks in Arrival (2016) and Carter Mitchum in Marriage Story (2019). In 2019 he won the Canadian Screen Award for Best Actor for his performance as Terry Sawchuk in Goalie.

O'Brien is married to actress Georgina Reilly, whom he met on the set of Republic of Doyle.

Compiled from published sources (en.wikipedia.org, imdb.com) · 16 September 2026How we write and check

Filmography

Beyond what we have reviewed, Mark O'Brien is known for Ready or Not (2019), Bad Times at the El Royale (2018), Hannibal (2013), The Darkest Minds (2018), How It Ends (2018), Anon (2018), Your Honor (2020) and Nuremberg (2025).

Marriage Story

2019 · as Carter Mitchum

Arrival

2016 · as Captain Marks