Who read the taped mission instructions in most original TV episodes?

Bob Johnson read the taped mission instructions in most episodes of the original *Mission: Impossible* television series.

Johnson provided the distinctive voice of the recorded messages that assigned missions to Dan Briggs or Jim Phelps. The message typically explained the objective, warned that the secretary would disavow knowledge of the IMF team's actions, and ended with the familiar self-destruct warning.

The voice was Robert Cleveland “Bob” Johnson, a voice actor who was generally not seen on screen and was not part of the regular acting ensemble. The recording device varied: episodes used tape recorders and, occasionally, phonograph records or other delivery methods. The recurring audio briefing became one of the program's defining conventions.

Peter Graves played team leader Jim Phelps, but he did not normally read the recorded instructions. Bruce Geller created the series, and Lalo Schifrin composed its famous theme; neither man was the regular voice of the mission recording. Those distinctions make Bob Johnson the canonical answer.