Consider the question. 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.

Answer this question based on the passage: who played mark on the tv show roseanne?
What is the step-by-step reasoning process to arrive at the answer: Glenn Martin Christopher Francis Quinn?
The important part for answering this question is: 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.