CBS Radio Mystery Theater (a.k.a. Radio Mystery Theater and Mystery Theater, sometimes abbreviated as CBSRMT) is a radio drama series created by Himan Brown that was broadcast on CBS Radio Network affiliates from 1974 to 1982, and later in the early 2000s was repeated by the NPR satellite feed. In New York City it was not aired by the then all-news WCBS but by its originating station, WOR, which produced and announced it as simply Radio Mystery Theater.

The format was similar to that of classic old time radio shows like The Mysterious Traveler and The Whistler, in that the episodes were introduced by host E. G. Marshall who provided pithy wisdom and commentary throughout. Unlike the hosts of those earlier programs, Marshall is fully mortal, merely someone whose heightened insight and erudition plunge the listener into the world of the macabre.

CBSRMT was broadcast each weeknight, at first with a new program each night. Later in the run, three or four episodes were new originals each week, and the remainder repeats. There were 1,399 original episodes. The total number of broadcasts, including repeats, was 2,969. Each episode was allotted a full hour of airtime, but after commercials and newscasts, each episode typically ran for around 45 minutes. - Wikipedia