Adventures of Sherlock Holmes or, Held for Ransom

Adventures of Sherlock Holmes; or, Held for Ransom is a 1905 American silent film directed by J. Stuart Blackton for Vitagraph Studios. It was the second film based on Arthur Conan Doyle's Sherlock Holmes stories, following the 1900 Mutoscope trick film Sherlock Holmes Baffled, and is usually regarded as the first attempt to film a "serious" Holmes adaptation. The scenario was by Theodore Liebler based on elements of Conan Doyle's novel The Sign of the Four.

Released on October 7, 1905, the film starred Maurice Costello as Sherlock Holmes, H. Kyrle Bellew as John Watson, with J. Barney Sherry in an unlisted role. The film was the first screen appearance of Costello, who later became regarded as one of the first "matinee idols". Robert Pohle notes that "Deprived of his voice in those early silent films, Holmes was also transformed from an intellectual, armchair detective into a more kinetic action figure—almost a sort of cowboy-in-deerstalker."

Although sometimes considered a lost film, fragments are still extant in the Library of Congress paper print collection. The film was shot on 35mm black-and-white film, running to one reel of 725 feet in length.