The Mysteries of Udolpho: A Romance is a Gothic novel by Ann Radcliffe, which appeared in four volumes on 8 May 1794 from G. G. and J. Robinson of London. Her fourth and most popular novel, The Mysteries of Udolpho tells of Emily St. Aubert, who suffers misadventures that include the death of her mother and father, supernatural terrors in a gloomy castle, and machinations of Italian brigand Signor Montoni. It is often cited as an archetypal example of the Gothic novel.
The popularity of The Mysteries of Udolpho helped cement the Gothic novel as a distinct genre, and has inspired many imitators since publication. It was a notable point of reference in Jane Austen's Northanger Abbey, which both satirises and pays homage to Gothic literature.