Armadale by Wilkie Collins is a novel by Wilkie Collins, first published in 1864–66. It is the third of his four 'great novels' of the 1860s: after The Woman in White (1859–60) and No Name (1862), and before The Moonstone (1868).

In the German spa town of Wildbad, the 'Scotchman' Mr. Neal is asked to transcribe the deathbed confession of Allan Armadale; his story concerns his murder of the man he had disinherited (also called Allan Armadale), who had subsequently married the woman he was betrothed to under false pretensions. Under Allan's instructions, the confession is left to be opened by his son once he comes of age.

Nineteen years later, the son of the murdered man, also Allan Armadale, rescues a man of his own age, Ozias Midwinter. The stranger reveals himself to Reverend Decimus Brock, a friend of Allan through his late mother, as another Allan Armadale (the son of the man who committed the murder). Ozias tells Decimus of his desperate upbringing, having run away from his mother and stepfather (Mr. Neal).

The Reverend promises not to disclose their relation to one another, and the young men become close companions. Ozias remains haunted by a fear that he will harm Allan as a result of their proximity, a fate warned of in his father's letter; this feeling intensifies when the pair spend a night on a shipwreck off the Isle of Man—as it turns out, the very ship on which the murder was committed. Also on the vessel, Allan has a mysterious dream involving three characters; Ozias believes that the events are a prophecy of the future.