In Hindu mythology, the serpent-demon who caused drought until Indra defeated him with the thunderbolt was Vritra.
Vritra appears prominently in the Rigveda as a powerful adversary of Indra, the storm and warrior deity. Vritra withholds the waters, often described as rivers or life-giving forces, and Indra releases them by striking him with the vajra, the thunderbolt weapon.
The myth presents a cosmic struggle between obstruction and the return of rain and flowing water. Vritra’s name is connected with the idea of enclosure or obstruction, matching his role as the being who holds the waters back.
Vritra is sometimes loosely grouped with nāgas, but he is not the same figure as Shesha, Vasuki, or Kaliya. Those serpents have different roles in Hindu stories, including supporting Vishnu, serving in the ocean-churning episode, and being subdued by Krishna.