This chapter explores how the Gothic romance of the eighteenth century splintered into different, allied forms of the Ghost, horror fiction, and the weird in the course of the nineteenth century. It is concerned with trying to offer distinct definitions of these modes, looking at historical narratives that might explain the emergence of secular horror and the category of the weird in the fin de siècle. Weird fiction has long been a marginal, overlooked, or invisible tradition that might stretch from Bulwer-Lytton via Arthur Machen to Algernon Blackwood and H. P. Lovecraft. It is also a category marked by the self-fashioning of a lineage that reaches back to the Gothic but finds a different route through the material. Since critical theory embraced horror and the weird as resistant categories for “thinking the unthinkable” in the twenty-first century, this area of scholarship illuminates how the nineteenth century is in a constant process of reconfiguration.