Norman Bates is the main antagonist from the movie and novel Psycho who was created by Robert Bloch. He and his mother had worked together, as Norman had killed people in his blackouts, including his own father and his mother removing the bodies. This had all been done to keep the bond between them.
Grand Theft Auto: San Andreas
Some players reported that Norman Bates will show up and kill the player in the Johnson House. Some players have also said his footsteps can be heard while in the wardrobe.
It is interesting to note that Norman's character was inspired by Ed Gein, another serial killer believed to be in the game. However, the myth is fake, as there is little evidence to support this myth, and it does not have much in the first place.
Grand Theft Auto V
At the Paleto Cove dock, a poster can be found at the small Bait and Tackle store on the dock. If you were to view it in the first person, it would read "NORMAN BAITS: For the mother of all catches.", being an obvious reference to Norman Bates and his mother, Norma.