A Discovery of Witches is a 2011 historical-fantasy novel and the debut novel by American scholar Deborah Harkness. It follows the story of Diana Bishop, a history of science professor at Yale University who, after accidentally finding an elusive, long-thought-lost manuscript, is compelled to embrace the magic in her blood that she has sought to keep out of her life and engage in a forbidden romance with charming vampire Matthew Clairmont.

A Discovery of Witches was first published in hardcover on February 8, 2011, by Penguin Books, becoming a New York Times Best Seller upon its release. It has since been released in paperback and also as an ebook. The novel has been translated into more than 36 languages. The book received mostly positive feedback from literary critics. It was praised for its intelligence and the mixture of history and fantasy, although some critics felt the plot was trite and the pacing was slow.