Former chorus boy who would become a star in "B" westerns, and later a successful comedy writer (under the name David Barclay) and TV director. O'Brien is notable as one of the relatively few success stories to emerge out of the drek of poverty row, where he blissfully worked for nearly a decade before landing work in the hypo-nasal Pete Smith's series of novelty shorts at MGM. In the mid-50's he gravitated toward comedy writing working on the Red Skelton Show, striking up a longtime friendship with series co-writer Sherwood Schwartz.