Solanum nigrum is a species in the Solanum genus, native to Eurasia and introduced in the Americas, Australasia and South Africa. Parts of this plant can be highly toxic to livestock and humans, and it's considered a weed. Nonetheless, ripe berries and cooked leaves are used as food in some locales; and plant parts are used as a traditional medicine.
The name Solanum nigrum has been commonly used to include many distinct but similar species, and more than one taxon may be represented in the material treated here under this name.

The Solanum nigrum complex - also known as Solanum L. section Solanum - is group of Solanum species with general black nightshade characteristics. Some of the major species within the Solanum nigrum complex are: Solanum nigrum, S. americanum, S. douglasii, S. opacum, S. ptychanthum, S.retroflexum, S. sarrachoides, S. scabrum, and S. villosum.