Bo Derek was virtually unknown when she appeared as Dudley Moore's fantasy girl in the midlife-crisis comedy 10, which premiered on Oct. 5, 1979. But this stunning 22-year-old introduced herself by jogging down the beach in slow motion, and then uninhibitedly stripping naked to bed Moore: Suddenly, male viewers knew exactly who she was and helped send the film over the $70 million mark.

Writer-director Blake Edwards had long been hunting for the ''ideal woman'' to lure Moore's character away from his girlfriend (Julie Andrews), but it took only one meeting with Bo (born Mary Cathleen Collins, and renamed by her Svengali-like husband John Derek, 30 years her senior) to end the search. ''I didn't have an agent, I wasn't working, I wasn't planning to work, or even hoping to work in the business,'' says Derek, whose only previous role was in 1977's Orca. ''I just went in, said hello, and came home with the part.''

The term bombshell is appropriate in her case, considering how her fame exploded. Bo's million-plus-selling poster made teenage boys say, ''Farrah who?'' Paparazzi stalked her at her home. Swingers everywhere began following Derek's 10 character's cue and revving up Ravel's ''Bolero'' for lovemaking. And women everywhere let hairdressers yank their scalps to duplicate her beaded cornrow look. ''I was surprised [at its popularity] because it took so long,'' she says. ''And it can be brutal on your looks.''

Derek was showered with offers to appear in movies, some for up to $1 million, but after one forgettable mainstream role with Anthony Hopkins in 1980's A Change of Seasons (which had an obligatory nude scene), she largely spurned studio films to star instead in her husband's soft-core fantasias, like 1981's Tarzan, the Ape Man and 1984's Bolero. It was easy for Bo not to obsess about her career, considering that at the time she had no passion for acting, and it wasn't like her husband was encouraging her to hone her craft: ''She's not an actress, she's a picture personality,'' John said in 1980.

From 1984 to 1991, Derek was nowhere to be seen, but she began taking acting seriously in the '90s, appearing in notably nonserious roles in 1995's Tommy Boy and the NBC prime-time soap Wind on Water, which was canceled after two weeks in 1998, the same year her husband died of heart failure at age 71.

Bo, now 44, has just completed her autobiography, Unbridled, due out in 2002. But no one will need reminding of her role in 10: In fact, people are always reminding her. ''When I go on stage or appear somewhere,'' she says, '''Bolero' is usually playing.''


Sign up for EW.com's The 25 newsletter!

Stay in the know and get EW.com's top 5 stories, 5 days a week (sent weekday afternoons).