Vṛtra

Vritra
King of deities Indra kills the vritrasura with a thunderbolt
Resemblance	Serpent or Dragon

In the early Vedic religion, Vritra (Sanskrit: वृत्र, vṛtra, lit. 'enveloper') is a serpent or dragon, the personification of drought and adversary of Indra. In Hinduism, Vritra is identified as an Asura. Vritra was also known in the Vedas as Ahi (Sanskrit: अहि ahi, lit. 'snake'). He appears as a dragon blocking the course of the rivers and is heroically slain by Indra.

According to the Rig Veda, Vritra kept the waters of the world captive until he was killed by Indra, who destroyed all the 99 fortresses of Vritra (although the fortresses are sometimes attributed to Sambara) before liberating the imprisoned rivers. The combat began soon after Indra was born, and he had drunk a large volume of Soma at Tvashtri's house to empower him before facing Vritra. Tvashtri fashioned the thunderbolt (Vajrayudha) for Indra, and Vishnu, when asked to do so by Indra, made space for the battle by taking the three great strides for which Vishnu became famous. Vritra broke Indra's two jaws during the battle, but was then thrown down by Indra and, in falling, crushed the fortresses that had already been shattered. For this feat, Indra became known as Vritrahan "slayer of Vritra" and also as "slayer of the first-born of dragons". Vritra's mother, Danu (who was also the mother of the Danava race of Asuras), was then attacked and defeated by Indra with his thunderbolt. In one of the versions of the story, three Devas - Varuna, Soma and Agni - were coaxed by Indra into aiding him in the fight against Vritra whereas before they had been on the side of Vritra (who they called "Father").