Gothic Horror is one of the oldest of the horror genres. Darker, edgier and on the Romanticism end of Romanticism.
In addition to being important to the horror genre, the first scifi, fantasy, romance, mystery, and adventure authors drew inspiration from Gothic horror, so it's sometimes considered the parent of all modern genre fiction.

Content:
Mary Shelley: Frankenstein

Bram Stoker:
Dracula
The Judge's House

Oscar Wilde: The Picture of Dorian Gray

Robert Louis Stevenson: The Strange Case of Dr. Jekyll and Mr. Hyde

Edgar Allan Poe:
The Tell-Tale Heart,
The Pit and the Pendulum,
The Cask of Amontillado,
The Masque of the Red Death,
The Black Cat,
The Fall of the House of Usher

Washington Irving: The legend of sleepy hollow

Sheridan Le Fanu: Carmilla

Henry James: The Turn of the Screw

Arthur Machen: The Great God Pan

Nikolai Gogol: The Viy