Joris-Karl Huysmans (February 5, 1848 – May 12, 1907) was a French novelist.

He was born in Paris. Huysmans started his literary career as a Naturalist writer with texts such as Marthe, Histoire d'une fille (1876). His novel À rebours (Against the Grain) (1884) broke from Naturalism and became the ultimate example of "decadent" literature. À rebours gained further notoriety as an exhibit during the trials of Oscar Wilde in 1895, during which the prosecutor referred to the novel as a "sodomitical" book. In 1891, the publication of La-Bas (Down There) attracted considerable attention for its depiction of Satanism in late 1880s France. His later works En Route (1895) and La Cathédrale (1898) are influenced by Catholicism. Huysmans was also known for his art criticism: L'Art moderne (1883) and Certains (1889). He was a founding member of the Académie Goncourt.

Joris-Karl Huysmans was interred in the Cimetière du Montparnasse, Paris, France.