A Nagaraja is a king of the various races of the nāga, the divine or semi-divine, half-human, half-serpent beings that reside in the netherworld (Patala), and can occasionally take human form. Rituals devoted to these supernatural beings have been taking place throughout South Asia for at least two thousand years.

In various Asian religious traditions, the Nagas are a divine, or semi-divine, race of half-human, half-serpent beings that reside in the netherworld (Patala), and can occasionally take human or part-human form, or are so depicted in art. A female naga is called a Nagi, or a Nagini. Their descendents are known as Nagavanshi. According to legend, they are the children of the sage Kashyapa and Kadru. Rituals devoted to these supernatural beings have been taking place throughout South Asia for at least 2,000 years. They are principally depicted in three forms: as entirely human with snakes on the heads and necks, as common serpents, or as half-human, half-snake beings in Hinduism, Buddhism, and Jainism.