Trivia

He was a teacher for 10 years before becoming an actor.

He is a fine fiddle player and can be seen playing it in Michael Collins (1996), Cold Mountain (2003) and also in The Banshees of Inisherin (2022).

He taught English, Irish & Physical Education at Belcamp College Secondary School in Dublin.

He has four sons from his marriage to Mary Gleeson: Domhnall Gleeson, Fergus Gleeson, Brian Gleeson and Rory Gleeson. Appeared with all his sons in the Irish television special Immaturity for Charity (2012).

He started acting at the age of 34.

He played Irish leader Michael Collins in The Treaty (1991). He later had a supporting role in the biopic Michael Collins (1996).

Has been in six films with Cillian Murphy such as Sweety Barrett (1998), 28 Days Later (2002), Cold Mountain (2003), Breakfast on Pluto (2005), Perrier's Bounty (2009) and In the Heart of the Sea (2015).

He has starred in feature films with two of his sons: Studs (2006) and Harry Potter and the Deathly Hallows: Part 1 (2010) with his eldest son Domhnall Gleeson, and The Tiger's Tail (2006) with his second youngest, Brian Gleeson.

Plays a professor of Defense Against the Dark Arts in Harry Potter and the Goblet of Fire (2005). This makes him the first, and to date, only actor to play a Hogwarts professor who has himself been employed as a teacher.

He has worked with 8 directors who have won an Oscar for Best Director: Ron Howard, Mel Gibson, Steven Spielberg, Martin Scorsese, Danny Boyle, Anthony Minghella, Robert Zemeckis, and Robert Redford.

His son Brian Gleeson played the young Joseph Lynch that Gleeson portrayed at an older age in Assassin's Creed (2016).

He won the Best Supporting Actor at the 2015 British Independent Film Awards for his performance as Inspector Arthur Steed in Suffragette (2015), beating his son Domhnall Gleeson who was nominated for his performance in Brooklyn (2015). The younger Gleeson accepted the award for his father.

Taught Maths at St. Joseph's Secondary school in Fairview, Dublin.

He is the only actor from the "Harry Potter" films to have co-starred with Daniel Radcliffe in his feature debut The Tailor of Panama (2001).

Played British Prime Minister Sir Winston Churchill in Into the Storm (2009). In Harry Potter and the Goblet of Fire (2005), he appears with Timothy Spall and Robert Hardy, both of whom have also played Churchill.

Has appeared in four films with his son Brian Gleeson and these include The Tiger's Tail (2006), Noreen (2010), Assassin's Creed (2016) and Psychic (2018).

Has appeared in seven films with his son Domhnall Gleeson and these are Six Shooter (2004), Studs (2006), Perrier's Bounty (2009), Harry Potter and the Deathly Hallows: Part 1 (2010), Noreen (2010), Calvary (2014) and Psychic (2018).

Has played two heads of state Winston Churchill in Into the Storm (2009) and Donald Trump in The Comey Rule (2020).

Has appeared in five films with Liam Neeson such as Michael Collins (1996), Gangs of New York (2002), Breakfast on Pluto (2005), Kingdom of Heaven (2005) and The Ballad of Buster Scruggs (2018).

Born on the same date as Marina Sirtis (of "Star Trek: The Next Generation (1987)" fame).