Donald E. Stewart (January 24, 1930 – April 28, 1999) was an American screenwriter, best known for his screenplay for Missing, which won the Academy Award for Best Adapted Screenplay, the Writers Guild of America Award, the London Film Critics’ Circle Award, a Christopher Award, and the BAFTA Award for Best Screenplay, all shared with the film’s director, Costa-Gavras.

After his passing, the widow of credited screenwriter Donald E. Stewart discovered the Hostiles script while moving houses. Stewart had never submitted the manuscript to any studios, and she was surprised to come across it. After seeing Crazy Heart (2009) and Out of the Furnace (2013), she felt that Scott Cooper was the right person to bring it to the screen.