Stewart (24 January 1930 – 28 April 1999) was an American-born 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, (www.christophers.org) and the BAFTA Award for Best Screenplay, all shared with the film's director, Costa-Gavras.
The screenplay for Missing is used in film schools for instruction in structure and development.
He also wrote or co-wrote the screenplays for the Tom Clancy trilogy of Jack Ryan films: The Hunt for Red October, Patriot Games and Clear and Present Danger.