Donald George Ingalls was an American screenwriter and television producer. During his 35-year career Ingalls wrote scripts for more than 70 episodes of network television, including Adam-12, Bonanza, The Big Valley, Fantasy Island, Gunsmoke, Have Gun-Will Travel, Honey West, Marcus Welby M.D., Police Story, Serpico, Star Trek, and The Virginian. Ingalls also wrote the script for the movie Airport 1975.