Colm is an Irish actor known worldwide for playing Miles O'Brien in Star Trek . The Next Generation (1987–1994) and Star Trek Deep Space Nine (1993–1999).

He has guest-starred on many TV shows including Law & Order and The Simpsons, and starred as Thomas Durant on Hell on Wheels.

He was born in Finglas, Dublin and began studying acting at age 14, and he entered the Abbey Theatre School of Acting after secondary school.

He became a member of the Irish National Theatre and worked for the next eight years in England, touring with several theatre companies, including a theatre group founded by John McGrath.

In 2017, Meaney won the Best Actor IFTA for his portrayal of Irish politician Martin McGuinness in the film The Journey. In 2020, he was listed at number 24 on The Irish Times list of Ireland's greatest film actors.