Mystery Science Theater 3000
The show first aired on a Minneapolis local channel called KTMA. The Comedy Channel, which would later become Comedy Central, picked up the show in 1989. Comedy Central decided to cancel the show six episodes into the seventh season. The Sci-Fi Channel then picked up the show for the last three seasons.
The framing plot of the show, which was really just a means to partially explain the movie-watching segments, changed over the course of the series. For the first season, the evil scientists Dr. Clayton Forrester and Dr. Laurence Erhardt trap the good-hearted janitor Joel Robinson on the "Satellite of Love" with the intention of torturing him by making him watch really bad movies. Once there, Joel builds robots for companionship. Robots "Tom Servo" and "Crow T. Robot" accompany Joel into the theater, while the robot "Gypsy" runs the higher functions of the ship and "Cambot" films the show. Once in the theater, Joel and "the bots" make fun of the movie, with the conceit that this will keep Joel sane.
In the third season of the show (the second season on Comedy Central), Dr. Erhardt was replaced by "TV's Frank," and the voice of Tom Servo was replaced as well. In the middle of the fifth Comedy Central season, the character of Joel was replaced by well-meaning temp Mike Nelson. TV's Frank left the show at the end of the sixth season, and the character of Pearl Forrester, Dr. Forrester's mother, was introduced to replace him. Dr. Forrester left at the end of the seventh, which was thought at the time to be the shows finale.
When the show was picked up by The Sci-Fi Channel, Dr. Forrester didn't return, which necessitated a change in Crow's voice. Pearl took over as the show's "villain", and added sidekicks "Bobo", a talking ape in Planet of the Apes style, and "Observer"/"Brain Guy", an allegedly incorporeal being who carries his brain in a dish.