There is a familiar critical narrative about the fin de siècle, into which gothic fiction fits very neatly. It is the story of the gradual decay of Victorian values, especially their faith in progress and in the empire. The self-satisfied (middle-class) builders of empire were superseded by the doubters and decadents. As Patrick Brantlinger writes, “After the mid-Victorian years the British found it increasingly difficult to think of themselves as inevitably progressive; they began worrying instead about the degeneration of their institutions, their culture, their racial ‘stock’” (230). And this late-Victorian anomie expressed itself in the move away from realism and toward romance, decadence, naturalism, and especially gothic horror. No wonder, then, that the 1880s and 1890s saw a surge of gothic fiction paranoiacally concerned with the disintegration of identity into bestiality (Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde, 1886), the loss of British identity through overpowering foreign influence (du Maurier's Trilby, 1894), the vulnerability of the empire to monstrous and predatory sexualities (Stoker's Dracula, 1897), the death of humanity itself in the twilight of everything (Orwell's The Time Machine, 1895). The Victorian Gothic, thus, may be read as an index of its culture's anxieties, especially its repressed, displaced, disavowed fears and desires. But this narrative tends to overlook the Victorians’ concerns with the terrifying possibilities of progress, energy, and self-assertion. In this essay I consider two oppositions that shape critical discussions of the fin-de-siècle Gothic – horror and terror, and entropy and energy – and I argue that critics’ exploration of the Victorians’ seeming preoccupation with the horrors of entropic decline has obscured that culture's persistent anxiety about the terrors of energy. I examine mid- to late-Victorian accounts of human energy in relation to the first law of thermodynamics – the conservation of energy – in both scientific and social discourses, and then I turn to Richard Marsh's 1897 gothic novel The Beetle as an illustration of my point: the conservation of energy might have been at least as scary as entropy to the Victorians.