Robert Louis Stevenson's 1886 novella The Strange Case of Dr. Jekyll and Mr. Hyde is about a physician, Henry Jekyll, who transforms himself into a brutal, murderous counterpart named Edward Hyde. Or, its about an evil murderous man named Edward Hyde iwho transforms himself nto a cordial, respected physician named Henry Jekyll. Given the fact that the transformation involves consumption of a medicinal potion concocted of special ingrediants, it is more likely that the underlying character is Dr. Jekyll. In any event, the story takes on the characteristics of what today are referred to as dissociative identity disorder, or schizophrenia -- the assumption of multiple personalities by an individual who cannot control the shift from one personality to another. As a lawyer named Gabriel John Utterson becomes intrigued by and investigates the violent incidences involving Edward Hyde, he gradually comes to the realization that his friend Dr. Henry Jekyll and Edward Hyde are one and the same. Meanwhile, Jekyll loses his ability to control when the transformation into Hyde will occur, and succumbs to the reality that he has created a murderer who he cannot control.
The Strange Case of Dr. Jekyll and Mr. Hyde is a classic of literature, and remains widely read today. It has also been adapted into stage and film versions.