One Day in September is a 1999 documentary film directed by Kevin Macdonald examining the 5 September 1972 murder of 11 Israeli athletes at the 1972 Summer Olympics in Munich, Germany. Michael Douglas provides the sparse narration throughout the film.

Kevin Glyn Buchanan Macdonald is a Scottish film director. His films include One Day in September (1999), a documentary about the 1972 murder of 11 Israeli athletes, which won him the Academy Award for Best Documentary Feature, the climbing documentary Touching the Void (2003), the drama The Last King of Scotland (2006), the political thriller State of Play (2009), the Bob Marley documentary Marley (2012), the post-apocalyptic drama How I Live Now (2013), the thriller Black Sea (2014), the Whitney Houston documentary Whitney (2018), and the legal drama film The Mauritanian (2021).