Vrtra in hindu mythology is the Hindu (Vedic) god of chaos. He is believed to be a primordial being existing before the formation of the cosmos, and was slain by the goddess Sarasvati.
In Hinduism, Vrtra (Sanskrit, «storm cloud») is a dark cloud of ignorance and sloth personified by a demon serpent that was vanquished by Indra. The story is the subject of several Vedic hymns, mentioned in the Rg Veda. A.G.H.
Sources:
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 289
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 1030