A striking actor with raven hair and piercing blue-green eyes, Gallagher has worked extensively on stage and screen. After appearing in the original Broadway production of Grease in the '70s, Gallagher segued into TV and film projects in the '80s, usually playing leads on the small screen and supporting parts on the big one. His convincing turn as a cheating yuppie in the Steven Soderbergh film Sex, Lies, and Videotape led to roles in high-profile projects such as Robert Altman's The Player and Tim Robbins' Bob Roberts. His career chugged along at a respectable pace until a part as a California patriarch on the hit prime-time soap The O.C. kicked it into overdrive in 2003.