CBS Radio Mystery Theater, also known as Radio Mystery Theater and Mystery Theater, was a radio drama series that aired on CBS Radio Network affiliates between 1974 and 1982, and later in the early 2000s on NPR satellite feed. Created by Himan Brown, the show followed a format similar to classic Old Time Radio programs like The Mysterious Traveler and The Whistler. E.G. Marshall hosted the show from January 1974 until February 1982 and introduced episodes with insightful commentary, inviting listeners into the world of the macabre.

The series encompassed a wide variety of genres, including horror, science fiction, historical drama, comedy, and seasonal dramas during the Christmas season. It featured classic adaptations, stories from famous writers, and original tales. With 1,399 original episodes, the series attracted a diverse array of talent, including renowned actors from stage, film, and TV, as well as notable voices from the golden age of radio.

Recorded in New York, CBSRMT captured the nostalgia of Old Time Radio, appealing to both older and younger audiences. The program's spine-chilling atmosphere and engaging storytelling made it a popular late-night treat for many listeners.