Uncle Silas by Sheridan Le Fanu is an 1864 Victorian Gothic mystery-thriller novel by the Irish writer J. Sheridan Le Fanu. Despite Le Fanu resisting its classification as such, the novel has also been hailed as a work of sensation fiction by contemporary reviewers and modern critics alike.
It is an early example of the locked-room mystery subgenre, rather than a novel of the supernatural (despite a few creepily ambiguous touches), but does show a strong interest in the occult and in the ideas of Emanuel Swedenborg, a Swedish scientist, philosopher and Christian mystic.
Like many of Le Fanu's novels, Uncle Silas grew out of an earlier short story, in this case "A Passage in the Secret History of an Irish Countess" (1839), which he also published as "The Murdered Cousin" in the collection Ghost Stories and Tales of Mystery (1851).
While this earlier story was set in Ireland, the novel's action takes place in Derbyshire; the author Elizabeth Bowen was the first to identify a distinctly Irish subtext to the novel, however, in spite of its English setting. It was first serialized in the Dublin University Magazine in 1864, under the title Maud Ruthyn and Uncle Silas, and appeared in December of the same year as a three-volume novel from the London publisher Richard Bentley. Several changes were made from the serialization to the volume edition, such as resolving the inconsistencies of names.