He began acting after signed up for acting classes at the Brendan Smith Academy and shortly after that he headed to New York, to study acting at The Neighbourhood Playhouse for two years. In 2007, Mullen began playing the role of Chrissie Williams’ abusive boyfriend Stuart McElroy in the BBC medical drama Holby City. Mullen left Holby City in 2008 as his character was arrested and taken away by the police.

Mullen is the first cousin of Larry Mullen, Jr. who is the drummer of Irish rock group, U2. He is married to actress Fiona Bell; they met on the set of Soldier Soldier in 1997. He has four children Hannah, Georgia, Cassie and Keir.

Conor Mullen (born 1961) is an Irish actor who played Stuart McElroy in Holby City and Aidan Doherty in the 2007 BBC1 drama series Rough Diamond. He was born in Dublin. Both parents were pharmacists and they had a chemist shop in Terenure. Mullen’s first job was as a sales merchandiser for Guinness and later Wrigley chewing gum. Then his father offered him a job. (By that stage, he was selling medical supplies instead of working in the Terenure pharmacy.)