Cotillard was born in Paris, France on September 30, 1975 to Jean Claude-Cotillard who is an actor, former mime, and a Molière Award winning director. Cotillard's mother Monique (known as Niseema) Theillaud, is also an actress and a drama teacher. She has two younger twin brothers, Quentin and Guillaume. Guillaume is a screenwriter and director. She began acting during her childhood, appearing on stage for her father's plays.