Keith McKinney used to be a famous Hollywood actor. Before the Great War, he was selected as a participant for the Vault 118 social experiment. He was then convinced by Bert Riggs and his wife to transfer his brain into a robobrain. He stars in the film The Fightn' Furies: Last Stand at Fort McGee being played at Eden Meadows Cinemas, as well as an unseen film titled Dutch Diggers of Dusseldorf.
He also has a secret love for Ezra, but implies that Ezra already knows and ignores him. Given Ezra's dark nature, namely killing Julianna for discovering his embezzlement, he probably leaves Keith in the dark for his personal enjoyment.