Here's why:
* Early Influence: Walpole's novel, though initially published anonymously, was a huge success and sparked a wave of imitations. It established many tropes that became hallmarks of gothic literature, including:
* Dark and ancient castles
* Supernatural elements like ghosts and mysterious prophecies
* Intrigue, mystery, and suspense
* Characters driven by passion and dark secrets
* Shifting Genre: While it wasn't the *first* novel to include elements of horror, "The Castle of Otranto" marked a shift in focus from the rationalism of the Enlightenment to the more emotional and dramatic aspects of the supernatural.
Other potential contenders:
* "The Monk" by Matthew Lewis (1796): This novel features more explicit horror and sexuality than "The Castle of Otranto," further solidifying the genre.
* "The Mysteries of Udolpho" by Ann Radcliffe (1794): While Radcliffe's novel is more focused on suspense and psychological horror, it also had a major influence on the gothic genre.
Ultimately, the "first" gothic horror novel is a matter of perspective. While "The Castle of Otranto" is widely recognized as the seminal work, many other early novels contributed to the development of this genre.