Leon Gast was an American documentary film director and producer.

He is perhaps best known for directing and producing the Oscar winning documentary feature film When We Were Kings (1996).

Gast was also at the helm of the documentaries Sporting Dreams (2015), Manny (2014), Smash His Camera (2010), Jumpshot (2004), 1 Love (2003), Celia Cruz: Guantanamera (1989), Hells Angels Forever (1983), Salsa (1976), B.B. King: Live in Africa (1974), and Our Latin Thing (1972).

For television, he produced the "The Trials of Muhammad Ali" episode of the documentary series Independent Lens, as well as the made-for-television documentary feature Fallen Champ: The Untold Story of Mike Tyson, in which he also served as an editor.

Gast died March 8, 2021, in Woodstock, New York. He was 84.