Strange Case of Dr Jekyll and Mr Hyde is a gothic novella by Scottish author Robert Louis Stevenson, first published in 1886. The work is also known as The Strange Case of Dr Jekyll and Mr Hyde, Dr Jekyll and Mr Hyde, or simply Jekyll & Hyde. It is about a London legal practitioner named Gabriel John Utterson who investigates strange occurrences between his old friend, Dr Henry Jekyll, and the evil Edward Hyde. The novella's impact is such that it has become a part of the language, with the phrase "Jekyll and Hyde" entering the vernacular to refer to people with an unpredictably dual nature: usually very good, but sometimes shockingly evil.
Stevenson had long been intrigued by the idea of how human personalities can affect how to incorporate the interplay of good and evil into a story. While still a teenager, he developed a script for a play about Deacon Brodie, which he later reworked with the help of W. E. Henley and which was produced for the first time in 1882. In early 1884, he wrote the short story "Markheim", which he revised in 1884 for publication in a Christmas annual. According to his essay, "A Chapter on Dreams" (Scribner's, Jan. 1888), he racked his brains for an idea for a story and had a dream, and upon wakening had the intuition for two or three scenes that would appear in the story Strange Case of Dr Jekyll and Mr. Hyde. Biographer Graham Balfour quoted Stevenson's wife Fanny Stevenson: