O'Hare, born in Chicago, attended Harvard, where he majored in English literature, and studied acting at the Juilliard School of Drama, as well as with Sanford Meisner. His first screen credit came in the noted 1976 miniseries "The Adams Chronicles." He was most famous for his starring role in the TV sci-fi series "Babylon 5" as Jeffrey Sinclair, commander of the space station of the title. O'Hare left the show at the beginning of its second season in 1996; the actor and producer J. Michael Straczynski both said the parting was amicable. He later reprised the Sinclair role in a guest appearance. He first appeared on Broadway in Players, starring Fred Gwynne, in 1978. The same year he appeared in a revival of George Bernard Shaw's Man and Superman that starred Philip Bosco. Later he replaced Stephen Lang in Aaron Sorkin's A Few Good Men as Lt. Col Nathan Jessep, the role Jack Nicholson would later play in the 1992 feature adaptation. The character famously utters the phrase, "You can't handle the truth." The actor had supporting roles in 1979 feature "The Promise," starring Stephen Collins and Kathleen Quinlan; 1981's "The Pursuit of D.B. Cooper"; and 1989's "Last Exit to Brooklyn," among other films. He also appeared in several telepics, guested on shows including "T.J. Hooker," "Kate & Allie" and "L.A. Law" and did an arc on daytime soap "One Life to Live." More recently he appeared on two episodes of "Law & Order."

Source: Variety