French novelist and dramatist who wrote her first and best-known novel, the international best-seller Bonjour Tristesse (1954), when she was 19 years old.

Educated at private and convent schools in France and Switzerland, Sagan attended the Sorbonne. She wrote the manuscript of Bonjour Tristesse in three weeks; it was made into a film in 1958. Among the novels that followed Bonjour Tristesse are Un Certain Sourire (1956; A Certain Smile), Aimez-vous Brahms? (1959), Les Merveilleux Nuages (1961; Wonderful Clouds), Un Profil perdu (1974; Lost Profile), De guerre lasse (1985; Engagements of the Heart, or A Reluctant Hero), and Un Sang d'aquarelle (1987; Painting in Blood). Most of Sagan's novels feature aimless people who are involved in tangled, often amoral relationships. Almost all her protagonists are young women involved sexually with older, world-weary men or, less frequently, middle-aged women and their young lovers. Her plays, which resemble her novels in content, were generally well received. They include Château en Suède (1960; Castle in Sweden) and L'Excès contraire (1987; Opposite Extremes). She also wrote film scripts, short stories, and nonfiction.