George Gissing (1857–1903) is one of the most rewarding and unsettling of the English writers of fiction associated with literary realism in the late nineteenth century. His early novels – beginning with Workers in the Dawn (1880) and culminating with The Nether World (1889) – dramatize the life of the suffering poor but also the anguished intellectual outcast, with whom he identified and saw as a victim of the deep-rooted Victorian class system and its equally entrenched hypocrisy. During his stormy early life Gissing engaged enthusiastically with socialism and at the same time he was drawn to the Positivist creed espoused by the French philosopher Auguste Comte (1798–1857). Almost immediately, however, he became disenchanted with Comte’s “religion of humanity” and developed a much darker disposition, strongly inflected by the aestheticism and ascetic detachment from the world and the “Will,” as advocated by the Pessimism of the German philosopher Arthur Schopenhauer (1788–1860). In this essay I argue that this apparently paradoxical philosophical volte face was inevitable from the outset and that Pessimism was always the dominant force in Gissing’s life. However, although Gissing embraced Schopenhauer’s aesthetic vision for artistic genius, he rarely achieved the asceticism on which Pessimism was founded; his anger and bitterness towards the hypocrisy of late-Victorian society stayed with him to the very end. Nevertheless, among contemporary, like-minded writers of fiction, including Thomas Hardy,George Meredith, George Moore, and Arthur Morrison, Gissing stands out as the Apostle of Pessimism.