The Bowser Room

The Bowser Room is a single, hidden room in Super Mario 64. It is a small room with a white floor and grey walls, and a picture of Bowser hung up on the wall. The purpose of this room or how to access it is unknown to this day, and appears to be a rare occurance in copies of the game.

Theories
Within Greenio's Lost Tapes, a room very similar to the Bowser Room appears in the video for 05.30.97. This implies that the Bowser Room is associated with the scrapped "bad" ending for Super Mario 64.

Trivia

 * It is said to be Miyamoto's favorite room.
 * The Bowser Room was mentioned in an Oney Plays Crash Bandicoot stream.