Richard Wagner’s musical and prose works are shot through with ideas, imagery, and speculation relating to race. Given the influence of racial theorising on almost every area of nineteenth-century European thought and culture, this is hardly surprising. Yet Wagner did not just absorb theories of race: he actively disseminated them, a fact that remains a troubling, if unavoidable part of his legacy. This chapter provides a selective overview of the history of scientific racism in Europe (especially Germany) from the Enlightenment era to the early twentieth century, focusing on the intersections of racial theory with aesthetics, comparative philology, and religious ideologies, including antisemitism. Special attention is devoted to Arthur de Gobineau’s influence on Wagner’s late essays, and the impact of those writings on the Bayreuth Circle, including Houston Stewart Chamberlain.