Dr. Jekyll and Mr. Hyde

The Strange Case of Dr. Jekyll and Mr. Hyde is an 1886 book written by Robert Louis Stevenson which has been adapted into numerous movies and stage productions. The story portrays the mild-mannered Doctor Henry Jekyll, who unleashes his monstrous alternate identity, Edward Hyde, by taking a chemical potion.

The story of Dr. Jekyll and Mr Hyde has become something of a cultural icon to describe people who exhibit contrasting and inconsistent moods or behaviors - known in psychological terms as dissociation. Dissociation is the principal attribute of people who suffer from dissociative identity disorder, which is more commonly known as multiple personality disorder or split personality disorder. Disassociation is also common in cases of borderline personality disorder. 

Numerous adaptations of the Dr. Jekyll & Mr. Hyde story have been portrayed on stage and film.

You can see some scenes from the 1932 classic "Dr Jekyll an Mr. Hyde" compiled here:

"The Strange Case of Dr. Jekyll and Mr. Hyde"