<P> Glenn Martin Christopher Francis Quinn ( May 28 , 1970 -- December 3 , 2002 ) was an Irish actor . While he was best known for his portrayal of Mark Healy on the popular ' 90s family sitcom Roseanne , Quinn also amassed a large fan base for his portrayal of Doyle , a half - demon , on Angel , a spin - off series of Buffy the Vampire Slayer . </P>
<P> Glenn Martin Christopher Francis Quinn ( May 28 , 1970 -- December 3 , 2002 ) was an Irish actor . While he was best known for his portrayal of Mark Healy on the popular ' 90s family sitcom Roseanne , Quinn also amassed a large fan base for his portrayal of Doyle , a half - demon , on Angel , a spin - off series of Buffy the Vampire Slayer . </P>
who played mark in the original roseanne series
who played mark in the original roseanne series
Glenn Martin Christopher Francis Quinn
Glenn Martin Christopher Francis Quinn