The Strange Case of Dr. Jekyll and Mr. Hyde is an example of late Gothic fiction. Much of Robert Louis Stevenson’s oeuvre fell broadly within the Romantic genre, and references to Romanticism are especially clear in his novels and longer works like Kidnapped and Treasure Island. Gothic literature is an off-shoot of Romanticism and began in the mid-18th century, continuing well into the Victorian period.
One of the most common tropes of both Romantic and Gothic literature is the “double,” or the doppelganger figure. In many Gothic novels, the main character encounters his own physical doppelganger. This double often possesses contrasting or opposing personality traits to the protagonist, despite their physical resemblance. The double often has sinister intentions or a goal of undermining or "replacing" the hero. The double was used by Gothic writers as a means of exploring duality in the human character and unexamined evil in the mind of the protagonist.
Though they bear a limited resemblance to one another, Hyde can easily be considered Jekyll’s double. Hyde often takes action in Henry’s name (such as when he signs a check on his behalf early on in the story) and seeks to supplant Henry’s primary personality, thus taking over his body, role, and position in the world.
An atmosphere of gloom, mystery, and suspense is also a key marker of Gothic fiction. In Dr. Jekyll and Mr. Hyde, the reticence of Utterson, Jekyll, Enfield, and Lanyon helps perpetuate a sense of mystery and intrigue. Their obsession with reputation leads to compulsive secret-keeping between and among them. Enfield avoids telling Utterson that Jekyll’s name is on Hyde’s check in the first chapter, Lanyon tells no one of Jekyll’s transformation, and Jekyll never talks about his struggle with Hyde to anyone until it’s too late. All of this secret-keeping contributes to a sense of suspense in the story, as Utterson’s (and the reader’s) discovery of Jekyll’s condition is continually delayed.
A thick mist or fog is a recurrent feature of Stevenson’s London, as are dark alleyways, twisting streets and rundown houses. These imposing and sometimes claustrophobic physical spaces are also a hallmark of Gothic fiction and reflect the personal, psychic, and emotional entrapment of the characters therein.