'Olalla' is a short story by the Scottish novelist, poet, essayist, and travel writer Robert Louis Stevenson. It was first published in the Christmas 1885 issue of The Court and Society Review, then re-published in 1887 as part of the collection The Merry Men and Other Tales and Fables. It is set in Spain during the Peninsular War.

The story is based on a dream that Stevenson had and in his 1888 essay 'A Chapter on Dreams' he describes the difficulties he had in fitting his vision into a narrative framework. Stevenson wrote the story at the same time as he was proofing 'Strange Case of Dr. Jekyll and Mr. Hyde' (published 1886).