The novel this movie was based on, "the Visitors" by Nathaniel Benchley, was published with art by Charles Addams, whose "Addams Family" comics were the basis for the TV series which made "Spirit is Willing" co-star John Astin a star. Furthermore, director William Castle previously worked directly with Addams, as the cartoonist provided drawings for Castle's 1963 film "The Old Dark House".
Debut of actress Jill Townsend .