Notable figure in the entertainment industry, O'Brien's career trajectory defied conventional expectations. Beginning as a chorus boy, he eventually transitioned to starring roles in "B" westerns, showcasing his versatility as a performer. Later, he adopted the pseudonym David Barclay and successfully ventured into comedy writing, as well as television direction.
A remarkable anomaly in the often-overlooked realm of poverty row productions, O'Brien worked diligently for nearly a decade before landing a breakthrough opportunity in the esteemed MGM studios. Specifically, he collaborated on a series of novelty shorts under the creative guidance of Pete Smith, renowned for his distinctive nasal tone.
In the mid-1950s, O'Brien's creative focus shifted towards comedy writing, with a notable stint on the Red Skelton Show. During this period, he formed a lasting professional bond with series co-writer Sherwood Schwartz, a partnership that would endure for many years to come.