This thesis explores late-nineteenth-century theories on suicide that emerged alongside a perceived ‘epidemic’ of suicides in Western societies, which brought the question of suicide into the public domain. Suicide was clearly a subject that fascinated and simultaneously horrified many Victorians and became a recurring theme in late-nineteenth-century Gothic fiction. However, it has received little critical attention, with the most extensive investigation into suicide in Victorian literature having been carried out by Barbara Gates in 1988. There has been no sustained investigation into the recurrent use of suicide in many late nineteenth-century Gothic novels, both the canonical and lesser-known stories. This thesis examines the extent to which some authors of late-Victorian Gothic fiction engaged with specific concerns, fears and suppositions relating to the perceived increase in suicide rates at the end of the century. It investigates how the authors of the ‘second wave’ of Gothic fiction incorporate ideas of suicide into their texts amid wider-reaching late-century fears and anxieties. Using primary sources including newspapers, various journals and periodicals, psychiatric and medical reports, reviews and case studies, the thesis examines the many speculative opinions about the era’s perceived ‘suicide epidemic’. It also explores the multiple ways in which authors of this Gothic fiction contextualised their own understanding of current debates, drawing into their works of fiction not just suicide theory but related themes such as inheritance, transgression, degeneration, social hypocrisies, egoism, passion, emotional and moral insanity. This gives a fascinating insight into the mutually informing relationship between the Gothic genre and medical, psychological and sociological theories and documentation pertaining to suicide in the era.