Peter Lindsay Weir AM (born August 21, 1944) is a retired Australian film director. He is known for directing films crossing various genres over forty years with films such as Picnic at Hanging Rock (1975), Gallipoli (1981), Witness (1985), Dead Poets Society (1989), Fearless (1993), The Truman Show (1998), Master and Commander: The Far Side of the World (2003), and The Way Back (2010). He has received six Academy Award nominations, ultimately being awarded the Academy Honorary Award in 2022 for his lifetime achievement career.

Early in his career as a director, Weir was a leading figure in the Australian New Wave cinema movement (1970–1990). Weir made his feature film debut with Homesdale and continued with the mystery drama Picnic at Hanging Rock (1975), the supernatural thriller The Last Wave (1977) and the historical drama Gallipoli (1981). Weir gained tremendous success with the multinational production The Year of Living Dangerously (1982).