Clément Thierry was the son of a Parisian doctor. He left school in 1946 but he had already been studying drama at the Vieux Colombier Theatre since 1945. His teachers had been Emile Darrs, Henri Rollan and Marcelle Géniat. He debuted at the Théâtre Antoine in July 1948 in Terence Rattigan`s "L`écurie Watson".