Claoxylon is a flowering plant genus in the spurge family, Euphorbiaceae, comprising dioecious subshrubs to small trees. It was first described as a genus in 1824. The genus is distributed in paleotropical areas: Madagascar through South and Southeast Asia, Malesia to Melanesia, Hawaiʻi, and Australia. Half of the species are in Malesia. According to a molecular phylogenetic study by Wurdack, Hoffmann & Chase (2005), Claoxylon is sister to Erythrococca (50 species, Africa), and together they form the top of a -like phylogeny.