Guillaume Gallienne (born 8 February 1972) is a French actor, screenwriter and film director. He has received two Molière Awards for his stagework and has won two César Awards, one for writing and the other for his performance in his autobiographical comedy film Me, Myself and Mum (2013).
Gallienne was born in Paris to French businessman Jean-Claude and Russian-Georgian aristocrat Melitta Gallienne, the third of four sons. From the age of 10, he attended La Salle Passy Buzenval where he was bullied for his effeminate personality. Two years later, after a nervous breakdown, he was sent to St John's College near Portsmouth in England. The death of a close cousin convinced him to take up acting at the age of 19. He attended Cours Florent for three years before studying under Daniel Mesguich, Stéphane Braunschweig and Dominique Valadié at the French National Academy of Dramatic Arts, graduating in 1998.