Castle Forrester is the ancestral home of the Forrester family on TV's Mystery Science Theater 3000. At the beginning of Season 9 Pearl Forrester and her traveling compansions Observer and Professor Bobo landed at the castle after Pearl felt drawn to its location. The trio began exploring the abandoned castle and discovered old documents that belonged to long-dead Forresters, such as the plans to strand a man on an island and send him terrible messages in a bottle.

The castle itself is built from grey stone and features a satellite dish with which to send horrible moves with. The castle itself is shaped like the letter 'F'. Pearl and her compansions moved into the castle and set up shop. For Seasons 9 and 10 of the series the castle acted as the Deep 13 from where the bad movies were sent. The castle remained basically as just a backdrop for the hijinks with the exception of the time Pearl moved it to the suburbs to avoid paying her monkey tax and another time when Mike Nelson managed to climb down a rope ladder from the Satellite of Love directly into the castle.

In episode 1013, the series finale, Pearl packed up her belongings and abandonded the castle as she left to become dictator of Qatar. Presumably the castle is still standing somewhere and waiting for another Forrester to take up residence.