A German Shepherd aficionado.
At the age of 10 he learned conjuring tricks from his neighbor, Harry Houdini.
Ex-father-in-law of Michael Anderson Jr..
Father, with Olga San Juan, of actress Maria O'Brien, TV producer Bridget O'Brien Adelman and Brendan O'Brien.
His production company, Tiger Productions, came from his childhood nickname, 'Tiger'.
In an interview, director Don Siegel recalled that during the production of China Venture (1953), he noticed that O'Brien was spending more and more time in his trailer before a scene, and was beginning to arrive late for shooting, which he had never done before. Suspecting that O'Brien might be secretly drinking before he went on camera--an experience Siegel had undergone with several well-known actors he had worked with--the director peeked through the windows of O'Brien's trailer one day and was surprised to see a young man reading O'Brien's lines to him. It turned out that O'Brien's eyesight and memory were beginning to fail him, he didn't want the studio to find out and fire him, so he had his assistant read him his lines and stage directions immediately before he was to shoot a scene so he wouldn't forget them on-camera.
Interred at Holy Cross Cemetery, Culver City, California, USA. Specific Interment Location: F, T54, 50.
O'Brien was originally cast as the photo-journalist Jackson Bentley (based on Lowell Thomas) in Lawrence of Arabia (1962). After O'Brien filmed several scenes, he suffered a heart attack and had to be replaced.
Performed a reading of "The Red Badge Of Courage" that was available as an LP.
Second actor to portray the title character on CBS Radio's "Yours Truly, Johnny Dollar" (1950-1952).
Was cast in Black Christmas (1974) as Lt. Kenneth Fuller, but the part was recast with John Saxon because of O'Brien's poor health. He was rumored to be suffering from Alzheimers.
Was original choice to play newspaper reporter Jackson Bentley in Lawrence of Arabia (1962), but health problems forced him to turn down the role, which eventually went to Arthur Kennedy.
Younger brother of screenwriter Liam O'Brien.