Witness is a 1985 American thriller film directed by Peter Weir and starring Harrison Ford and Kelly McGillis. The screenplay by William Kelley, Pamela Wallace, and Earl W. Wallace focuses on a detective protecting a young Amish boy who becomes the target of a ruthless killer after he witnesses a brutal murder in Philadelphia's 30th Street train station.

The film was nominated for eight Academy Awards and won two, for Best Original Screenplay and Best Film Editing. It was also nominated for seven BAFTA Awards, winning one for Maurice Jarre's score, and was also nominated for six Golden Globe Awards. William Kelley and Earl W. Wallace won the Writers Guild of America Award for Best Original Screenplay and the 1986 Edgar Award for Best Motion Picture Screenplay presented by the Mystery Writers of America. The film is also notable as the screen debut of future star Viggo Mortensen.