The Outsider by Howard Phillips Lovecraft

"The Outsider" is a short story by American horror writer H. P. Lovecraft. Written between March and August 1921, it was first published in Weird Tales, April 1926. In this work, a mysterious man who has been living alone in a castle for as long as he can remember decides to break free in search of human contact and light. "The Outsider" is one of Lovecraft's most commonly reprinted works and is also one of the most popular stories ever to be published in Weird Tales.
"The Outsider" combines Horror, Fantasy, and Gothic Fiction to create a nightmarish story, containing themes of loneliness, the abhuman, and the afterlife. Source: Wikipedia