Mylène Demongeot (born Marie-Hélène Demongeot; 29 September 1935 – 1 December 2022) was a French film, television and theatre actress and author with a career spanning seven decades and more than 100 credits in French, Italian, English and Japanese speaking productions. Demongeot became a star at age 21 with her portrayal of Abigail Williams in The Crucible (1957) which garnered her a BAFTA Award for Most Promising Newcomer to Leading Film Roles nomination and the best actress prize at the socialist Karlovy Vary International Film Festival. Some other notable film roles include Elsa in Otto Preminger's Bonjour Tristesse (1958), alongside Deborah Kerr and David Niven, and as Milady de Winter in Les Trois Mousquetaires (1961).

A "veteran of cinema" who started as one of the blond sex symbols of the 1950s and 1960s, she managed to avoid typecasting by exploring many film genres including thrillers, westerns, comedies, swashbucklers, period films and even pepla, such as Romulus and the Sabines (1961) opposite Roger Moore or Gold for the Caesars (1963).