Colm J. Meaney (/ˈkɒləm/; Irish: Colm Ó Maonaigh; born 30 May 1953) is an Irish actor. Known for his performances across screen and stage, he has received seven nominations from the Irish Film & Television Academy, winning twice for 2001's How Harry Became a Tree, and 2017's The Journey. Other film credits include Roddy Doyle's Barrytown franchise, Con Air, Layer Cake, The Damned United, Get Him to the Greek, and The Snapper, for which he was nominated for the Golden Globe Award for Best Actor in a Motion Picture - Comedy or Musical, and won the Silver Hugo Award for Best Actor at the 1993 Chicago International Film Festival.

On television, Meaney is best known for his portrayal of Miles O'Brien in both Star Trek: The Next Generation (1987-1994) and Star Trek: Deep Space Nine (1993-1999), appearing in a total of 225 episodes. Other television credits include five seasons as Thomas C. Durant on the AMC western Hell on Wheels (2011-2016), James Burbage on the TNT historical fiction series Will (2017), and Finn Wallace on the Sky Atlantic crime series Gangs of London (2020). Meaney's numerous guest appearances include roles on Moonlighting, MacGyver, Murdoch Mysteries, Law & Order, The Simpsons, and It's Always Sunny in Philadelphia.

Also a veteran of the theatre, Meaney has starred on Broadway and the West End in Eugene O'Neill's The Iceman Cometh and A Moon for the Misbegotten, Tennessee Williams' Cat on a Hot Tin Roof, and Hugh Whitemore's Breaking the Code. Additionally, he has appeared in numerous productions with the National Theatre of Ireland, including Sean O'Casey's Juno and the Paycock, The Silver Tassie, and The Shadow of a Gunman.

In 2020, Meaney was ranked 24th on The Irish Times list of "The 50 Greatest Irish Film Actors of All Time". In 2025, he received the Irish Film & Television Academy's Lifetime Achievement Award.

Meaney was born in Glasnevin, Dublin, the son of Kathleen and Patrick Meaney, who was a van driver for Johnston, Mooney, & O'Brien. His brothers are Liam, Padraig, and Sean Meaney. He developed a love of acting at the age of 14, and after completing his leaving cert matriculated to the Abbey Theatre School. Upon completing his studies, Meaney joined the company of the National Theatre of Ireland.

In 1971, Meaney joined the company of the National Theatre of Ireland, appearing in 24 productions over the next nine years. Credits from this period include William Shakespeare's The Winter's Tale, W. B. Yeats' King Oedipus, George Bernard Shaw's Saint Joan, Dion Boucicault's Arrah-na-Pogue, and Sean O'Casey's Juno and the Paycock. For much of this period, Meaney split his time between Dublin and London, touring the UK with several theatre companies, including the 7:84 theatre group founded by John McGrath. Meaney made his Off-West End debut in 1975, appearing in McGrath's plays Fish in the Sea at the Half Moon Theatre and Yobbo Nowt at the Shaw Theatre. The following year he appeared in a stage adaptation of Lin Piao's History of the Tenth Struggle at the Institute of Contemporary Arts. Meaney made his American stage debut in 1982 at the Great Lakes Shakespeare Festival, where he would remain a summer company member until 1985. Credits from this period include William Shakespeare's Henry V, J. M. Synge's The Playboy of the Western World, Dylan Thomas' A Child's Christmas in Wales, C. P. Taylor's And a Nightingale Sang, and the American premiere of The Life and Adventures of Nicholas Nickleby. The play is an 8½ hour-long stage adaptation of the Charles Dickens’ novel of the same name, performed in two parts. The production was a critical and commercial success, later transferring to Merle Reskin Theatre in Chicago, Illinois.

Meaney made his Off-Broadway debut in 1984, appearing as Kevin in Hugh Leonard's The Poker Sessions at Theater Off Park. In 1986 he relocated from New York City to Los Angeles. That same year he starred in Sławomir Mrożek's Alpha, Harold Pinter's The Birthday Party, and Peter Sheridan's Diary of a Hunger Strike, all at the Los Angeles Theatre Center. Meaney's performance in the latter earned him a Drama-Logue Award nomination for Best Actor in a Play. In 1987, Meaney appeared as Mick Ross in the American premiere of Hugh Whitemore's Breaking the Code at the Kennedy Center in Washington, D.C. Later that same year the production transferred to the Neil Simon Theatre on Broadway. From 1992 to 1993 Meaney appeared in a multi-city tour of Tom Stoppard's Every Good Boy Deserves Favour, directed by his Star Trek co-star Patrick Stewart. Tour venues included Orange County Symphony in Garden Grove, CA; The Chicago Theatre in Chicago, Illinois, and The Fox Theatre in Minneapolis, Minnesota. In 1999 Meaney starred in Peter Parnell's stage adaptation of John Irving's The Cider House Rules at the Atlantic Theater Company. Meaney won an Obie Award for his performance.

Meaney made his West End debut as Phil Hogan in the 2006 revival of Eugene O'Neill's A Moon for the Misbegotten at The Old Vic. Directed by Howard Davies, the cast also featured Kevin Spacey and Eve Best. For his performance, Meaney was nominated for the Olivier Award for Best Performance in a Supporting Role. The following year the production transferred to the Brooks Atkinson Theatre on Broadway. Meaney would later return to Broadway in the 2018 revival of Eugene O'Neill's The Iceman Cometh at Bernard B. Jacobs Theatre. Directed by George C. Wolfe, the cast featured Denzel Washington, Bill Irwin, David Morse, Tammy Blanchard, and Austin Butler. In 2023, after more than a 40-year absence, Meaney returned to the Irish stage in Landmark Productions' revival of the Enda Walsh play Bedbound at the Galway International Arts Festival. Starring opposite his daughter Brenda Meaney, the production later transferred to an additional engagement at the Olympia Theatre, Dublin.