"Strange Case of Dr. Jekyll and Mr. Hyde", published in 1886 by Robert Louis Stevenson, is about a man who transforms between two personae: Dr. Henry Jekyll and Mr. Edward Hyde. It is a perfect example of the Gothic genre.

The phrase 'Jekyll and Hyde' is sometimes used colloquially to refer to someone whose actions cannot be reconciled with each other.

In this story, Mr. Utterson, a lawyer and friend of Dr. Jekyll’s, is bothered by a will written by his friend that completely benefits a strange fellow named Mr. Hyde. To protect his friend, Mr. Utterson begins investigating Mr. Hyde, only to discover some truths about his friend that he could never have...