Greyhound is a 2020 American war film directed by Aaron Schneider and starring Tom Hanks, who also wrote the screenplay. The film is based on the 1955 novel The Good Shepherd by C. S. Forester, and follows a US Navy commander on his first assignment commanding a multi-national escort destroyer group of four, defending an Allied convoy from U-boats during the Battle of the Atlantic. The film also stars Stephen Graham, Rob Morgan, and Elisabeth Shue.

Cecil Louis Troughton Smith, known by his pen name Cecil Scott "C. S." Forester, was an English novelist known for writing tales of naval warfare, such as the 12-book Horatio Hornblower series depicting a Royal Navy officer during the Napoleonic Wars.