Vanessa is a genus of brush-footed butterflies in the tribe Nymphalini. It has a near-global distribution and includes conspicuous species such as the red admirals (e.g., red admiral, Indian red admiral, New Zealand red admiral), the Kamehameha, and the painted ladies of the Cynthia group (formerly a subgenus): Painted lady, American painted lady, West Coast lady, Australian painted lady, etc. For African admirals, see genus Antanartia. Recently, several members traditionally considered to be in the genus Antanartia have been determined to belong within the genus Vanessa. The name of the genus may have been taken from the character Vanessa in Jonathan Swift's poem "Cadenus and Vanessa," which is the source of the woman's name Vanessa. In the poem Vanessa is called a "nymph" eleven times, and the genus is closely related to the previously-named genus Nymphalis. Though the name has been suggested to be a variant of "Phanessa", from the name of an Ancient Greek deity, this is unlikely. The name of the deity is actually not "Phanessa" but Phanes. Johan Christian Fabricius, the entomologist who named this genus, normally used the original forms of the names of classical divinities when he created new scientific names. North American species in the genus overwinter as adults.

A fossil species, V. amerindica, is known from a specimen found in the Chadronian-aged Florissant Lagerstatte, from Late Eocene Colorado, and coexisted with several other extinct butterfly taxa.