Marie-Thérèse Walter (July 13, 1909 – October 20, 1977) was the French mistress and model of  Pablo Picasso from 1927 to about 1935, and the mother of his daughter, Maya Widmaier-Picasso. Their relationship began when she was seventeen years old; he was 45 and still living with his first wife, Olga Khokhlova . It ended when Picasso moved on to his next mistress, artist Dora Marrr.

In 1935, Marie became pregnant. When Picasso's wife, Olga, was informed by a friend that her husband had a longtime mistress who was expecting a child, she immediately left Picasso with their son Paulo and moved to the South of France. Picasso and Olga never divorced, because Picasso wanted to avoid the even division of property dictated by French law; instead, they lived separately until her death in 1955.

Picasso and Marie's daughter, María de la Concepción, called "Maya", was born on 5 September 1935.

In 1940, Marie and Maya moved to Paris, Boulevard Henri IV no 1, since the house at Le Tremblay-sur-Mauldre was occupied during World War II.

Picasso supported Marie and Maya financially, but he never married Marie.

On 20 October 1977, four years after Picasso's death, Marie-Thérèse committed suicide by hanging herself in the garage at Juan-les-Pins, South of France.

In 2004, Maya's son and Marie-Thérèse's grandson, Olivier Widmaier Picasso, published a biography of his famous grandfather titled Picasso: The Real Family Story.

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