"Dr. Jekyll and Mr. Hyde" is a quick read, just give it a chance. (Unfortunately, unlike Stevenson's original readers, we already know that Jekyll & Hyde are the same person, a revelation that comes late in the novel.) Out of all the classic horror novels in the initial post, "Dracula" was the most enjoyable. (Although "Phantom of the Opera" is very rereadable, as well.) Like "Frankenstein," Victor Hugo's "Hunchback of Notre Dame" also takes some effort to get through. (It's strange to think that "Frankenstein" was actually written by a teenager; few of our teens today could even READ it, let alone write it.)