Someone in the Dark is a collection of fantasy and horror short stories by author August Derleth. It was released in 1941 and was the second book published by Arkham House. 1,115 copies were printed, priced at $2.00. In Thirty Years of Arkham House, Derleth implied that this title had sold out by the end of 1944.

However, more than twenty years later, in 1967, Derleth listed Someone in the Dark in an Arkham House bulletin with this announcement: "We have acquired a small stock of this title, Derleth's first collection of macabre tales, published in 1941. They will be sold at $5.00 the copy to patrons interested in acquiring the book..." Derleth was being disingenuous in suggesting these 'unearthed' copies were the 1941 edition. The additional 300 copies were printed in offset by Hunter Publishing Co. in Winston-Salem in 1965, the reprint probably authorized by Derleth himself. (In The Arkham House Companion, Sheldon Jaffery quotes a letter that seems to indicate this). The 1965 reprint are a quarter-inch higher than the originals, and are bound with headbands (not present in the 1941 first editions).

The 1965 edition is scarce. While it is not generally considered an official Arkham House publication, it is considered an essential acquisition for Arkham House completists.

A paperback reprint was issued by Jove Books in 1978.