In Hinduism, Agastya is a legendary sage or rishi. He is reputed to have traveled to south India to teach the people there of the Vedic religion. On the way the Vindhya Range in central India, which had been growing uncontrollably to enormous height, bowed low out of respect to Agastya, accounting for their low height in the modern day. Agastya was also one of the great devotees of Lord Shiva, and after praying Lord Shiva, Lord Shiva himself taught him the language of Tamil, which he learned aptly. One story goes that once the demons had taken refuge in the ocean and it was difficult for the gods to vanquish them, so they went to Sage Agastya for help. Then, after hearing the gods, the sage drank the entire ocean water and withheld it within him until the demons were destroyed.

He plays a part in many stories in the Hindu tradition, including a small role in the story of Rama. The Lalitha sahasranama, which describes the 1000 names of Devi is said to been taught to him.

He is also said to have recited a hymn to Surya, Aditya Hridayam, to Rama on the battlefield before fighting with Ravana.