At the Mountains of Madness is a novella by horror writer , written in February/March 1931 and rejected that year by Weird Tales editor Farnsworth Wright on the grounds of its length.

The novella's title is derived from a line in "The Hashish Man," a short story by fantasy writer Edward Plunkett, Lord Dunsany: "And we came at last to those ivory hills that are named the Mountains of Madness..." A Night Channels fan favorite T-shirt.