CBS Radio Mystery Theater (a.k.a. Radio Mystery Theater and Mystery Theater, sometimes abbreviated as CBSRMT) was 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 carried by the NPR satellite feed.

The format was like that of classic old time radio shows like The Mysterious Traveler and The Whistler, in that the episodes were introduced by a 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 (in a manner like that of "The Man in Black" on yet another old-time radio program, Suspense).

As with Himan Brown's prior Inner Sanctum Myster ...