Ralston was a prolific television writer, authoring episodes of many series such as The Wild Wild West, Ben Casey, Gunsmoke, I Spy and Hawaii Five-O. He also wrote a few films, most notably the screenplay for the 1971 film Willard, based on the 1968 novel Ratman's Notebooks by Stephen Gilbert. Gilbert Ralston was born in New Castle, County Down, Ireland. He died in Mount Pleasant, South Carolina, USA from congestive heart failure in 1999.