Sherlock Holmes is a 2009 period mystery action film starring Robert Downey Jr. as the character of the same name created by Sir Arthur Conan Doyle. The film was directed by Guy Ritchie and produced by Joel Silver, Lionel Wigram, Susan Downey, and Dan Lin. The screenplay written by Michael Robert Johnson, Anthony Peckham, and Simon Kinberg was developed from a story by Wigram and Johnson. In addition to Downey Jr. as Holmes, Jude Law portrays Dr. John Watson. The film, set in 1890, follows eccentric detective Holmes and his companion Watson attempting to foil a mysticist's plot to gain control of Britain by seemingly supernatural means. Rachel McAdams stars as Holmes' former adversary Irene Adler and Mark Strong portrays villain Lord Henry Blackwood.

The film was widely released in North America on 25 December 2009, and on 26 December 2009 in the UK, Ireland, the Pacific and the Atlantic. Sherlock Holmes received mostly positive critical reaction. The film grossed $524 million worldwide, becoming the eighth highest-grossing film of 2009. Downey won the Golden Globe Award for Best Actor in a Musical or Comedy. The film was also nominated for two Academy Awards, Best Original Score and Best Art Direction. A sequel, Sherlock Holmes: A Game of Shadows, was released in 2011, with a third film in the works to be directed by Dexter Fletcher.