What is the name of the heroine in Ann Radcliffe's 'The Mysteries of Udolpho'?

The heroine of Ann Radcliffe’s The Mysteries of Udolpho is Emily St. Aubert.

Emily is the novel’s central character and viewpoint figure. At the beginning, she lives with her father in Gascony and shares his love of poetry, music and the natural world. After her mother’s death and then her father’s illness and death, Emily is drawn into a series of frightening journeys, family secrets and apparent supernatural events.

Much of the novel’s action takes place at Udolpho, a remote Italian castle controlled by the intimidating Montoni. Emily is threatened with confinement and pressured over her inheritance, while mysterious rooms, veiled objects and strange sounds test her courage. Radcliffe frequently builds suspense through the “explained supernatural”: terrifying scenes eventually receive rational explanations rather than confirming genuine ghosts.

Emily’s love story with Valancourt forms another major thread. Rumours temporarily convince her that he has become morally corrupt, but the truth is more complicated. Published in four volumes on 8 May 1794, the novel became one of the defining works of the Gothic tradition and was later referenced and parodied in Jane Austen’s Northanger Abbey.