Heart of Darkness (1899) is a novella by Polish-English novelist Joseph Conrad about a narrated voyage up the Congo River into the Congo Free State in the so-called heart of Africa. Charles Marlow, the narrator, tells his story to friends aboard a boat anchored on the River Thames. This setting provides the frame for Marlow's story of his obsession with the ivory trader Kurtz, which enables Conrad to create a parallel between what Conrad calls "the greatest town on earth", London, and Africa as places of darkness.

Central to Conrad's work is the idea that there is little difference between so-called civilised people and those described as savages; Heart of Darkness raises questions about imperialism and racism.

Originally issued as a three-part serial story in Blackwood's Magazine to celebrate the thousandth edition of the magazine, Heart of Darkness has been widely re-published and translated into many languages. Famously, the story provided the inspiration for Francis Ford Coppola's 1979 film Apocalypse Now. In 1998, the Modern Library ranked Heart of Darkness 67th on their list of the 100 best novels in English of the twentieth century.