Actor J.T. Walsh, one of Hollywood's top character actors who played Jack Nicholson's suicidal lieutenant colonel in "A Few Good Men" and a mental patient in "Sling Blade," died of a heart attack Friday. He was 54. Walsh died at Grossmont Hospital after falling ill at a San Diego-area resort hotel Friday morning, said his publicist, Cynthia Snyder.

Walsh, who had been active in community theater, was discovered by a director in 1974 and began working in off-Broadway shows. He met playwright David Mamet in 1976 and won a role in the first performance of "American Buffalo."His big break came when he was cast in another Mamet play, "Glengarry Glen Ross," on Broadway in 1984.

In just over a decade, Walsh appeared in more than two dozen films, including "Nixon," "Hoffa," "Tequila Sunrise," "Backdraft," "Blue Chips," "Wired" and "Red Rock West."