intense, introspective stage and film actor, widely regarded as the foremost interpreter of playwright Eugene O'Neill (O'Neill, Eugene).

Because of the bitterness and disillusionment expressed by his father, onetime stage and film leading man Jason Robards, Sr. (1892–1963), the younger Robards avoided acting in his youth. He served in the Naval Reserve as a radioman during the years 1940–46; he was present at the bombing of Pearl Harbor, and he later received the Navy Cross. Upon his discharge, he enrolled at the American Academy of Dramatic Arts, where he studied with Uta Hagen. Billed as Jason Robards, Jr., he made his first professional New York stage appearance in 1947, in a children's theatre production of Jack and the Beanstalk. Supplementing his acting income by working as a cab driver and a schoolteacher, he spent several years playing small roles onstage and in radio and television before he won a lead role in the 1953 Broadway production American Gothic.

Full stardom came Robards's way in 1956 when he played the self-delusional traveling salesman Hickey in the revival of Eugene O'Neill's (O'Neill, Eugene) The Iceman Cometh. That same year, he created the role of sensitive young alcoholic Jamie Tyrone, Eugene O'Neill's alter ego, in Long Day's Journey into Night. He subsequently starred in such O'Neill works as Hughie, A Moon for the Misbegotten, and A Touch of the Poet—all of which, like Iceman and Long Day's Journey, were directed by José Quintero (Quintero, José). Robards's other theatrical credits include his Tony Award-winning performance in Budd Schulberg (Schulberg, Budd)'s The Disenchanted (1958); additional honours were bestowed upon him the following year for his work in Lillian Hellman (Hellman, Lillian)'s Toys in the Attic.

In films since The Journey (1959), Robards was occasionally criticized for delivering overly theatrical screen performances, especially when he repeated his stage roles in the movie versions of Long Day's Journey into Night (1962) and A Thousand Clowns (1965). He appeared in such negligible films as The St. Valentine's Day Massacre (1967), in which he was singularly miscast as Al Capone, and Murders in the Rue Morgue (1971). Nevertheless, he earned two consecutive Academy Awards for his subtle, well-modulated performances as The Washington Post editor Ben Bradlee in All the President's Men (1976) and detective novelist Dashiell Hammett (Hammett, Dashiell) in Julia (1977). He received a third Oscar nomination for his interpretation of yet another “real-life” character, Howard Hughes (Hughes, Howard), in Melvin and Howard (1980). Robards's later films included Philadelphia (1993), A Thousand Acres (1997), and Magnolia (1999).

Robards continued to divide his time between stage, film, and television assignments well into the late 1990s, earning an Emmy Award for his performance as lawyer Henry Drummond in the 1988 TV-movie version of Inherit the Wind. His sons Jason Robards III and Sam Robards also pursued acting careers. The third of Robards's four wives was actress Lauren Bacall (Bacall, Lauren).