- This article is about the film version of the character. For the original literary version of the character, see Norma Bates (literary). For the Bates Motel version, see Norma Bates (Bates Motel).
"A boy's best friend is his mother."―Norman Bates[src]
Norma Bates was the domineering mother of Norman Bates. After Norman murdered her, he developed a murderous split personality based on her.
As a young woman, Norma and her sister, Emma were both in love with the same man. He decided to marry Norma and they had a child, Norman Bates. Emma, mentally unstable and extremely jealous, kidnapped Norman, believing him to be the son she should have had with Norma's husband. Norman was returned and Emma was institutionalized.
Norma was extremely controlling of her son's life and preached to him that all women – except herself – were whores and that sexual intercourse was sinful. On one occasion, Norma found a womens' undergarment catalog in Norman's room and reprimanded him, forcing him to throw it away.
On another occasion, Norman doused her with orange flower water and Norma playfully wrestled with him until she felt him have an erection. Thrown into a rage, she put him in a dress and lipstick and called him a girl as she locked him in a closet in an attempt to make him forget about his penis.
Soon, Norma began seeing Chet Rudolph, who she planned to marry after he received a divorce. A jealous Norman poisoned them both with strychnine and staged the scene to look like a murder-suicide perpetrated by Norma.
Norman later stole his mother's corpse and mummified it. He began to act as though she was still alive and would hear her speak to him. He also believed that she was responsible for several murders that took place on the motel property when, in reality, Norman had developed a split personality of his mother. When the Norma personality took over, he would dress up as her and speak with her voice.
After twenty-two years of being institutionalized, Norman was able to fully resist the "Mother" personality. However, after efforts by Lila and Mary Loomis – the sister and niece of Marion Crane, respectively – to return him to his insanity, the "Mother" personality became evident once more. Furthermore, Norma's sister, by then a co-worker of Norman, convinced him that she was his biological mother. He killed her and used her corpse in the same way he did Norma's.
Following several more murders as "Mother," Norman was told the truth about his mother and he destroyed Emma's mummified corpse as well as the "Mother" personality. Although he would be institutionalized again, he noted that he was "finally free."
Four-and-a-half years later, after his final release, Norman saw visions of his mother as he destroyed his childhood home.