Gothic Horror is one of the oldest of the horror genres. Darker, edgier and on the Romanticism end of Romanticism Versus Enlightenment, it tends to play on both the thrill and the fear of the unknown, and places a great importance on atmosphere. It's usually heavily symbolic, sometimes even dreamlike. 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.

Gothic fiction is usually used as a synonym or is the name given to Gothic horror stories that are saturated with the above mentioned scifi, fantasy, romance, mystery, or adventure elements.

The name "Gothic" comes from a kind of architecture from The Middle Ages (christened as such by those who considered it barbaric in comparison to classical architecture, the name coming from the barbarian tribe of the Goths). There were a lot of Gothic ruins lying around Britain, and people in the 18th and 19th centuries developed an interest in them because (a) ruins are always kind of mysterious and melancholy and creepy and (b) they evoked the time period they were built in, which was thought of as a barbaric time where people believed in (and did) all kinds of weird stuff. For this reason, most early Gothic horror novels were set in that era. They were usually also set in Catholic countries, because the Brits who wrote them considered Catholicism sinister (yet also kinda cool).

The renewed interest in Gothic stuff also led to the Gothic Revival movement in architecture, but for the purposes of this article we're not so interested in that.

Horace Walpole's The Castle of Otranto, written in 1764, is considered the first Gothic horror novel. Walpole was a big fan of William Shakespeare and proudly declared that he borrowed most of the tropes from his idol's plays, particularly Hamlet, Macbeth, and Romeo and Juliet. Ann Radcliffe helped popularize the genre, and authors such as Matthew Lewis, Ludwig Flammenberg, Eliza Parsons, Eleanor Sleath, and Francis Lathom finished out the eighteenth century Gothic horror writers. The beginning of the nineteenth century saw Gothic horror being parodied by authors like Jane Austen, but there were still straight examples provided by authors such as Lord Byron and Mary Shelley. By the time the Victorian era rolled around Gothic horror was beginning to run out of steam, but there were still quite a few people writing it — in fact, most of the Gothic horror authors and works you've heard of probably come from this era, such as Edgar Allan Poe and the Brontë sisters. There were a few more notable Gothic authors in the early 20th century, but by the 1950s or so the genre had given way to modern Horror.

Universal and Hammer Films are responsible for successfully adapting this genre onto the big screen. For a modern take on the genre see Gaslamp Fantasy and Supernatural Fiction.

For a list of tropes used in the Gothic horror genre see Index of Gothic Horror Tropes.

Authors who wrote partially or entirely in the Gothic fiction genre include:

Eighteenth Century

Horace Walpole — Trope Maker and gave us Haunted Castle.
Ann Radcliffe — author of, among others, The Mysteries of Udolpho. Notably replaced real supernatural events with the Scooby-Doo Hoax.
William Beckford — author of Vathek.
Matthew Gregory Lewis — gave us the Sinister Minister with The Monk.
Eleanor Sleath
Eliza Parsons
Francis Lathom
Carl Friedrich Kahlert alias Ludwig Flammenberg
Carl Grosse alias Marquis de Grosse
Regina Maria Roche

Pre-Victorian Nineteenth Century

Charles Robert Maturin — Melmoth the Wanderer.
Eaton Standard Bennot
Jane Austen — wrote the most famous Parody of the genre, Northanger Abbey.
E. T. A. Hoffmann — most important German author of Gothic fiction.
Lord Byron — his Byronic Hero was a major contribution to Gothic fiction.
Mary Shelley — gave us Frankenstein's Monster and is considered the first Science Fiction writer.
John William Polidori — wrote the first vampire novel, TheVampyre.

Victorian

Edgar Allan Poe — most important American author of Gothic fiction; wrote the first Great Detective Mystery.
George W.M. Reynolds
Charles Dickens — gave us Victorian London or at least the Hollywood version of it.
Edward Bulwer-Lytton — of It Was a Dark and Stormy Night fame.
Charlotte Brontë — gave us Mad Woman In The Attic in Jane Eyre.
Emily Brontë — Wuthering Heights.
Wilkie Collins — The Woman In White.
Louisa May Alcott — While best known for Little Women, She Also Did reasonably successful "sensational" Gothic romances such as A Modern Mephistopheles under the pen name of A.M. Barnard, and one called A Long Fatal Love Chase that everyone in her own lifetime found too scandalous to publish.
Sheridan Le Fanu — gave us the Occult Detective and Lesbian Vampires in the form of Carmilla.
Robert Louis Stevenson — gave us the Jekyll and Hyde trope through Dr Jekyll And Mr Hyde.
Oscar Wilde — The Picture of Dorian Gray.
Arthur Machen — The Great God Pan.
George Du Maurier — author of the novel Trilby, which was the Trope Namer and possibly the Trope Maker for The Svengali.
Robert W. Chambers — paved the way for the emergence of the Cosmic Horror Story with The King in Yellow.
Bram Stoker — gave us Dracula and Überwald.
Henry James — The Turn of the Screw.
Ambrose Bierce — another precursor to the Cosmic Horror Story.
Arthur Conan Doyle

Post Victorian

Algernon Blackwood
Hugh Walpole
Marjorie Bowen
Montague Rhodes James
William Hope Hodgson
Daphne du Maurier — granddaughter of the above-mentioned George du Maurier; wrote Rebecca and the original short story on which The Birds was based.