Updated through 4/26.
Le Point and L'Express are among the French news outlets reporting that Marie-France Pisier has died at her home in Saint Cyr sur Mer at the age of 66. First mention is generally going to her work with François Truffaut; her debut, after all, was in his Antoine and Colette, a short film that was part of the 1962 anthology Love at Twenty and she would reprise the role in Stolen Kisses (1968) and Love on the Run (1979). The film many will be thinking of today, though, is Jacques Rivette's Céline and Julie Go Boating (1974). In 1981, Julia Lesage described her role in the film's development: "Script credit is given to Juliet Berto, Dominique Labourier, Bulle Ogier, Marie-France Pisier, and Jacques Rivette…. According to Berto, she and Labourier imagined creating a combination of Persona and What Ever Happened To Baby Jane? in a film with two female protagonists. Berto said, 'Each of them could have been the other. To be an actress, that's to be someone ambiguous. They would pursue each other; they would meet. That could be magic or not. At that moment, there'd be a mystery with a phantom house and phantom people.' Berto and Labourier wanted the phantom characters to be invisible; Rivette wanted them visible. With Ogier, Pisier, and friend Eduardo de Gregorio, they spent the summer working out the decor, costumes, and dialogue of that interior story."
Pisier won a Best Actress Cesar and, in general, wider international recognition for her starring rolle in Jean-Charles Tacchella's 1975 comedy Cousin, cousine and she's appeared in three of André Téchiné's films: French Provincial (1975), Barocco (1976) and The Brontë Sisters (1978).
From TCM: "Pisier attempted to crack the American film industry with The Other Side of Midnight (1977), a dull misfire adapted from a Sidney Sheldon novel. She did not fare well with either her TV credits (the 1979 ABC miniseries The French Atlantic Affair and 1980's Scruples) or her second Hollywood film French Postcards (1979). Returning to France, she continued to work; in 1990, Pisier made her directorial debut with Le Bal du gouverneur/The Governor's Party, which she adapted from her own novel. Still gorgeous, she also offered a marvelous turn as the vulgar Madame Verdurin in Time Regained/Le Temps retrouve (1999) Raúl Ruiz's adaptation of Proust."
Her last onscreen appearance will be in a documentary on Jean-Paul Belmondo which will see its premiere in Cannes in a couple of weeks. The French papers report that she'd planned to attend.
Update, 4/25: "In 1974," Ronald Bergan reminds us in the Guardian, "she appeared in the most outrageous and amusing sequence in Buñuel's penultimate film, Le Fantôme de la Liberté (The Phantom of Liberty), where she is among the elegant guests seated on individual lavatories around a table from which they excuse themselves to go and eat in a little room behind a locked door…. More recently, she was an iconic presence in Christophe Honoré's homage to the French new wave, Dans Paris (2006). Pisier also directed two films, Le Bal du Gouverneur (The Governor's Party, 1990), starring Kristin Scott Thomas and adapted from Pisier's own novel about some of her childhood spent in New Caledonia in the Pacific, and Comme un Avion (Like an Airplane, 2002), a family drama based on the death of her own parents."
Update, 4/26: "Off-screen, the liberal-minded Pisier was an ardent defender of women's rights and legal abortion, having signed Simone de Beauvoir's April 1971 manifest demanding the legalization of the procedure," notes André Soares at the Alt Film Guide. "She was also a breast cancer survivor. A statement credited to French president Nicolas Sarkozy lauded Marie-France Pisier for representing 'that supreme elegance born out of the most perfect simplicity.'"