There is a newly-coined genre of horror literature called “Lovecraftian horror.” However, this type of horror has been lurking in modern horror fiction and various productions of arts and entertainment for over half a century. H. P. Lovecraft—whom the genre is named after—was one of the undeniable masters of modern horror fiction. He created a unique form of horror referred to as “cosmic horror” which is the main ingredient for the creation of this genre of horror. This thesis introduces and analyzes Lovecraft’s cosmic horror through his life and texts. By presenting a dissection of some of his most remarkable texts—such as “The Call of Cthulhu"—the creation process and gradual evolution of cosmic horror is more clearly demonstrated. Finally, cosmic horror and Lovecraftian elements are analyzed through various productions of pop culture—mainly cinema—to depict how cosmic horror secured Lovecraft’s position as a prominent icon in pop culture, in addition to an indisputable master of modern horror fiction.