"I know she used to get very scared about that scene," said the director's daughter, Pat Hitchcock, who had a small part in "Psycho" as a co-worker of Leigh's.
Leigh died at her Beverly Hills home, with husband Robert Brandt and her daughters, actresses Jamie Lee Curtis and Kelly Curtis, at her side. She was 77.
"She died peacefully," Heidi Schaeffer, a spokeswoman for Jamie Lee Curtis, said Monday.
Leigh had suffered from vasculitis, an inflammation of the blood vessels, for the past year.
The blond beauty had 60-odd film and TV roles in a career whose highlights included playing Frank Sinatra's romantic interest in "The Manchurian Candidate" and Charlton Heston's abducted bride in Orson Welles' "Touch of Evil."
Yet the shower scene in "Psycho" became Leigh's defining moment, the role earning her an Academy Award nomination for supporting actress.
Leigh played embezzling office worker Marion Crane, who checks into the Bates Motel and never checks out. Dressed as his own mother, psychotic hotel clerk Norman Bates (Anthony Perkins) repeatedly stabs Marion in the harrowing sequence, which was accompanied by the shrieking violins of composer Bernard Herrmann's score.
"`Psycho' scared the hell out of me when I saw it finished. Making it and seeing it are two different things," Leigh told The Associated Press in 2001, when "Psycho" was picked No. 1 on the American Film Institute's top 100 list of most thrilling U.S. movies. "That staccato music and the knife flashing. You'd swear it's going into the body. I still don't take showers, and that's the truth."
The scene left countless moviegoers sneaking the occasional peak around the shower curtain to make sure the bathroom was clear of knife-wielding lunatics. It also was a drastic departure from Hollywood convention, defying expectations of audiences who until that point had identified with Leigh as the movie's main character.
"I think first of all it was having a big movie star playing the part and dying early in the movie," said Pat Hitchcock. "That was the shock value."
Leigh had a classic storybook introduction to Hollywood. Born in Merced, Calif., on July 6, 1927, she was attending the University of the Pacific when retired screen star Norma Shearer saw her photograph at a ski resort. Shearer recommended the teenager to talent agent Lew Wasserman, who negotiated a contract at MGM for $50 a week.
Dubbed Janet Leigh (her birth name was Jeanette Helen Morrison) she starred at 19 in her first movie, "The Romance of Rosy Ridge," opposite Van Johnson, and her salary was quickly boosted to $150 a week. She became one of MGM's busiest stars, appearing in six movies in 1949.
Among her films: "Act of Violence" (with Van Heflin), "Little Women," "Holiday Affair" (Robert Mitchum), "Strictly Dishonorable" (Ezio Pinza), "The Naked Spur" (James Stewart), "Living It Up" (Martin and Lewis), "Jet Pilot" (John Wayne), "Bye Bye Birdie" (Dick Van Dyke) and "Safari" (Victor Mature).
Leigh had been married twice before coming to Hollywood: to John K. Carlyle, 1942, the marriage later annulled; and Stanley Reames in 1946, whom she divorced two years later.
In 1951, she married Tony Curtis when their stardoms were at a peak. Both their studios, MGM and Universal, worried that their immense popularity with teenagers would be hindered if they were married.
Aided by a splurge of fan magazine publicity, their appeal rose. They appeared in four films together, including "Houdini" and "The Vikings." The "ideal couple" divorced in 1963. In her 1984 autobiography, "There Really Was a Hollywood," she refrained from criticizing Curtis.
"Tony and I had a wonderful time together; it was an exciting, glamorous period in Hollywood," she said in an interview. "A lot of great things happened, most of all, two beautiful children (Kelly Curtis and Jamie Lee Curtis)."
Her 1964 marriage to businessman Brandt was longer lasting.
Leigh appeared in Jamie Lee's 1980 thriller "The Fog" and co-starred again with her daughter in one of her last roles in 1998's slasher sequel "Halloween H2O: 20 Years Later."
In recent years, Leigh was very choosy about acting projects and except for her daughter's flicks, declined regular offers to trade on her "Psycho" fame with other horror roles, said her agent, John Frazier.
"Every year at this time of the year, she would be approached to do something tied into Halloween," Frazier said. "She never did that. She thought it would have cheapened it."