Previously, the actor guest starred on the short-lived series "The Outsiders", appeared in the pilot of Aaron Spelling's popular drama "Beverly Hills, 90210" (both Fox, 1990) and had a non-speaking role in the music video for the Richard Marx hit "Satisfied". Shortly after making his "Roseanne" debut, Quinn portrayed actor George Chakiris in the Patty Duke TV biopic "Call Me Anna" (CBS, 1990) Following the series' 1997 final episode, the actor could be seen on television with a guest role in the NBC sitcom "Jesse" (1998). In 1999, he would return to series work, with a regular role on "Angel", a spin-off of The WB's popular supernatural series "Buffy the Vampire Slayer", following the vampire Angel's quest to redeem himself in the City of Angels, with Quinn's Doyle, a newly appointed advisor, at his side. The role of this do-gooding demon called for the actor to speak in his native brogue, and his portrayal of the lively character provided comic relief to the somewhat dark drama. Despite this charming turn and Doyle's popularity with viewers, the actor was dropped after a handful of episodes.
Quinn made his big screen debut with a supporting role as the drummer of the featured band in the 1950s set rock musical "Shout" (1991), offering a good performance in a relatively large role which allowed him to draw upon his experience playing drums with local bands in Dublin. He next appeared as the strong-willed boyfriend of an ill girl stalked by the titular deranged surgeon in the horror drama "Dr. Giggles" (1992). Quinn was additionally featured in the 1995 independent "Live Nude Girls," "Campfire Tales", a 1998 episodic horror film, and "At Any Cost," a 2000 VH1 movie. In December 2002 Quinn was found dead in a friend's North Hollywood home after an apparent drug overdose.