Marie-Helene Demongeot was born on September 28, 1936, in Nice, France, into a family of actors. She studied dramatic art with Marie Ventura.Her film career began with a role in Les Enfants de l'amour (Children of Love 1953). Demongeot rose to international fame in the late 1950's. She was together with Gary Cooper for the opening of the first escalator to be installed in a cinema, at the Rex Theatre in Paris, on June 7, 1957. She had a memorable seduction scene opposite Yves Montand in Les Sorcieres de Salem (The Crucible 1957). Her first notable leading role was in Be Beautiful But Shut Up (aka.. Blonde for Danger 1958), where she played a 17-year-old jewel smuggler. She further developed her image of a manipulative blond mistress playing opposite David Niven in Bonjour tristesse (1958), and became permanently locked in the cliché image of a humorous seductress after her supporting role opposite Alain Delon in the 1959 comedy Le Donno sono deboli (Three Murderesses). Her chance to update the image came in the period films. She played manipulative and coquettish Andromeda opposite Steve Reeves in La Bataille di Marathon (The Giant of Marathon. 1959) and the leading role of Rea opposite Roger Moore in L'Enlevement des sabines (Romulus and the Sabines. 1961).Among her best known film-works are the role of manipulative Milady de Winter in Les Trois mousquetaires (The Three Musketeers 1961) and the role of 'Helen' in all three of the Fantomas films. Mylene Demongeot became one of the blond sex symbols in the 50's, 60's and 70's French cinema. Although she gradually fazed out of her stereotypical image of a French coquette, she looked pretty convincing in the image of a mid-aged Madame, which she developed in the 80's and 90's. Demongeot was also a producer during the 1980. She is the co-owner of the Kangarou Films production company, which she founded with her late husband Marc Simenon. She made a comeback in 36 Quai des Orfevres (2004). In 2005, in Cannes, France, Mylene Demongeot announced her new work with director/writer Jacques Fieschi in "La Californie" (2006), based on a short story by Georges Simenon. Her last film-work was in Camping (2006).