Lansium is a genus of plants in the family Meliaceae, containing at least three species. The species Lansium domesticum is a tropical fruit-bearing tree that is cultivated in tropical Southeast Asia, and on a much smaller scale elsewhere in the tropics. Other previously named species are now placed in the genera Aglaia and Reinwardtiodendron.
The genus was named in 1807 by the Portuguese botanist José Francisco Corrêa da Serra. As of 2021, the Catalogue of Life recognizes three species of Lansium.
Phylogenetic studies suggest the following relationships amongst closely related genera: