Edgar Allan Poe was instrumental in the development of the horror genre through his innovative use of psychological suspense and macabre themes. His works, including "The Tell-Tale Heart" and "The Fall of the House of Usher," explored the darker aspects of the human psyche, delving into madness and mortality. Poe's emphasis on atmosphere, emotion, and detailed narrative techniques influenced countless writers and established a blueprint for future horror literature. Furthermore, his contributions to detective fiction with "The Murders in the Rue Morgue" laid the groundwork for the genre's evolution. Poe's blend of terror and intricacy revolutionized storytelling, making him a pivotal figure in American literature.