Quinn was born in Dublin, Ireland, and moved to the United States with his mother and two sisters in 1988. His first role was as a pool shark in the Richard Marx video "Satisfied". He later had a major role in the John Travolta film Shout, where he shared a screen kiss with Gwyneth Paltrow, and went on to have roles in a number of other movies and television series. His most notable roles to date have been as Becky's husband, Mark, on Roseanne and half-demon Doyle on the WB's _"Angel" (1999/I)_ .


Though originally from Dublin, Ireland, most of Quinn's roles have called for him to hide his Irish accent and don an American one. The WB series "Angel" (1999) was his first role in an American series where he was allowed to use his own brogue. Quinn's first screen kiss was in Shout (1991) with Gwyneth Paltrow. While still playing Mark on "Roseanne" (1988), Quinn also took a role as youngest son Cedric on a series called "Covington Cross" (1992). But while "Roseanne" (1988) filmed in the US, "Covington Cross" (1992) was filmed in England, which gave the actor one hell of a commute. Attended Clonkeen College, a Roman Catholic Christian Brothers school, in Blackrock, near Dublin. Did dead-on impersonations of "Sesame Street" (1969)'s Grover and Christopher Walken. He was spotted by casting director Johanna Ray, who helped him get representation. Favorite band was U2. Worked in a factory, painted houses and waited tables before getting discovered. He died at a friend's house when he overdosed on heroin. Grew up in Cabinteely, Dublin, Ireland down the street from Cinematographer / Producer Noel Donnellon and Animator / Director Paul Donnellon. Though allowed to use his native Irish accent in the show "Angel" (1999), it was so thick that he had to occasionally "Americanize" it so you could understand what he was saying. This sometimes made it sound as if is accent was fading in and out. While playing Mark on "Roseanne" (1988), Quinn took a role as youngest son Cedric on the British series "Covington Cross" (1992). With "Roseanne" (1988) filmed in the US and "Covington Cross" (1992) was filmed in England, he was often commuting.