Peter Lindsay Weir AM (born 21 August 1944) is an Australian retired film director, spanning diverse film genres over forty years with films such as Picnic at Hanging Rock (1975), Gallipoli (1981), The Year of Living Dangerously (1982), Witness (1985), Dead Poets Society (1989), Fearless (1993), The Truman Show (1998), and Master and Commander: The Far Side of the World (2003). Among his successes, Weir has received six Academy Award nominations, an Academy Honorary Award in 2022 for his lifetime achievement career, and an honorary lifetime achievement award at the Venice Film Festival (Golden Lion) in 2024.

Weir's career began as a leading figure in the Australian New Wave cinema movement (1970–1990) with his feature film debut with Homesdale, followed by Picnic at Hanging Rock (1975), The Last Wave (1977), and Gallipoli (1981). His success continued with the multinational production The Year of Living Dangerously (1982). Following this, Weir directed a diverse group of American and international films, many of which were major box office hits including Academy Award-nominated films like Witness (1985), Dead Poets Society (1989), Green Card (1990), The Truman Show (1998), and Master and Commander: The Far Side of the World (2003). His final feature before retirement was The Way Back (2010). Born in Sydney in 1944, Weir started his career in film after meeting fellow students at the University of Sydney. His interest in film led to his work at Sydney television station ATN-7, where he created experimental short films and worked on satirical comedy programs.