Dullea, who now does theater almost exclusively, has enjoyed success on the stage equal to or greater than that of his film career, although no single project brought him more name recognition than "2001". He made his Broadway debut opposite Burl Ives in "Dr Cook's Garden" (1967) and garnered critical acclaim as Donny Dark, the blind boy, in The Great White Way's "Butterflies Are Free" (1969). He returned to Broadway as Brick in the revival of Tennessee Williams' "Cat on a Hot Tin Roof" (1974) and also acted in Broadway productions of "P S Your Cat Is Dead" (1975) and "Doubles" (1985). Leaving Hollywood for good in 1982, Dullea and his third wife, the late director Susan Fuller, ran the Theatre Artists Workshop of Westport (CT), a non-profit organization modeled along the lines of the Actor's Studio. He starred Off-Broadway in "the Other Side of Paradise" (1992), a one-man show about writer F Scott Fitzgerald, and also appeared in a production of "Molly Sweeney" (1997) at the Playmakers Repertory Company in North Carolina.