The Zero Hour (aka Hollywood Radio Theater) was a 1973–74 American radio drama anthology series hosted by Rod Serling. With tales of mystery, adventure and suspense, the program was broadcast for two seasons. Some of the scripts were written by Serling.

The radio series debuted on September 3, 1973, in syndication, and was picked up by the Mutual Broadcasting System in December. The original format featured five-part dramas broadcast Monday through Friday with the story coming to a conclusion on Friday. Including commercials, each part was approximately 30 minutes long. Mutual affiliates were free to broadcast the series in any available time slot that they wished.

In 1974, still airing five days a week, the program changed to a full story in a single 30-minute installment with the same actor starring throughout the week in all five programs. That format was employed from late April 1974 to the end of the series in July 1974.