Neptunia may refer to:
Neptunia (plant), a genus of plants within the subfamily Mimoseae Neptunia (gastropod), an emendation of Neptunea, a genus of sea snails Neptunia (Darkwing Duck), a cartoon character in the television series Darkwing Duck Neptunia, Uruguay, a resort location in Canelones Department, Uruguay , an Italian liner launched in 1931 , an Italian tanker launched in 1945 Hyperdimension Neptunia, a video game series Neptunia, a Roman colony at Taranto, Italy