David Mark Weber (born October 24, 1952) is an American science fiction and fantasy author. He has written several science-fiction and fantasy book series, the best-known of which is the Honor Harrington science-fiction series. His first novel, which he worked on with Steve White, sold in 1989 to Baen Books. Baen remains Weber's major publisher.

Many of his stories have military, particularly naval, themes, and fit into the military science fiction genre. He frequently places female leading characters in traditionally male roles. One of his most popular and enduring characters is Honor Harrington, whose alliterated name is an homage to C.S. Forester's character Horatio Hornblower and her last name from a fleet doctor in Patrick O'Brian's Master and Commander. Her story, together with the "Honorverse" she inhabits, has been developed through 16 novels and six shared-universe anthologies, as of spring 2013.

In addition to the Honor Harrington series, Weber has explored the Honorverse with series of novels not directly related to Honor Harrington. He has collaborated with authors such as Steve White, Linda Evans, John Ringo, and Eric Flint.