He had been a poet, cartoonist, and labor organizer before World War II, when he served in the Signal Corps.
He became an overnight success six years later when his first screenplay, the romantic comedy Here Comes the Groom, with Bing Crosby and Jane Wyman, earned him an Oscar nomination in 1951.
[3] The play remains popular in amateur theatres, partly because there are so many roles to be filled:[4] the industrialist Mr. Pennypacker is a loveable bigamist with 17 children.
[4] O'Brien collapsed in his wife's arms and died of a heart attack at his Los Angeles home at age 83.
[4] His son, Devin Liam O' Brien, has been an associate producer of the Academy Award television broadcast.