My sons recently watched and enjoyed The League of Extraordinary Gentlemen, a flight of fancy in which several famous fictional characters team up to fight fictional evil. The group includes Dr. Jekyll, Tom Sawyer, Dorian Gray, The Invisible Man, Alan Quartermaine (not the one from General Hospital) and a woman vampire whose name I have forgotten. I was not able to suspend my disbelief, but the boys loved it, especially the character of Hyde, who, subject to modern special effects, is quite huge, like a pro wrestler who has eaten several other pro wrestlers.
I decided that I needed to read them Robert Louis Stevenson's original novel, Dr. Jekyll and Mr. Hyde, although I fear that its more subtle horror will leave them disappointed. This is a book oft interpreted, but the interpretations are rarely true to the spirit of the story.
For me, the horror is in the metaphor that we all have the potential to be Hyde; that it doesn't require a potion, sometimes, for us to go mad, to lose control, to shock others with our altered personalities. And yet, like Jekyll, we must take responsibility for those altered states.
And while I'm on the subject of altered states, I must mention that today is the birthday of the great Franz Kafka, who famously wrote of Gregor Samsa and his Metamorphosis into a cockroach. (You can download the e-book for free).
Given the choice between the existential horror and the real horror, I think I would rather be Hyde. :)