Question: When is the director of film The Great Impostor 's birthday?
Sentence (from "Robert Mulligan"): Robert Patrick Mulligan (August 23, 1925 – December 20, 2008) was an American film and television director best known as the director of humanistic American dramas, including "To Kill a Mockingbird" (1962), "Summer of '42" (1971),
Relevant evidence: Yes