Agastya is one of the most famous ṛṣis (sages or seers) frequently met with in Hindu religious lore. He is the seer of several Ṛgvedic mantras (Ṛgveda Saṁhitā 1.166 to 191). He is a brahmarṣi, the son of Pulastya and Havirbhuk. Sage Agniveśya is his disciple.
According to another version he was the son of Mitra and Varuṇa, and was born in a kumbha or jar. Hence the names Kumbhaja, Kumbhodbhava, Kalaśīsuta and so on. Vasiṣṭha was his brother. He married Lopāmudrā (also known as Kāverī), the princess of Vidarbha and begot a son Dṛḍhāsya, also known as Idhmavāha. A man of vast knowledge and severe austerity he is said to have destroyed the demons Ilvala and Vātāpi, stunted the growth of the Vindhya mountain which was growing recklessly, obstructing the light of the sun, drunk the waters of the ocean to expose the demons Kālakeyas who were killed by the gods, to have been honoured by Rāma when he was living in the Daṇḍakāraṇya and to whom he gave divine weapons and also taught the Ādityahṛdaya-hymn later and brought about reconciliation between Indra and the Maruts.
Though Agastya is not enumerated among the Saptarṣis (the seven great sages), he is included among the progenitors of ‘gotra’ geneology. He has been accorded a stellar status and identified with Canopus, the brightest star in the sky of southern India.
In the annals of Tamil religious lore and literature, Agastya is the accredited originator of the Tamil language, the author of the maiden grammar of that language and the first president of the first organization of Tamil litterateurs. He is also credited with the authorship of several works on medicine, mysticism and magic. One work called Agastya Saṁhitā which deals with ritualistic worship is available. It is part of Pāñcarātra literature. He is said to have visited several South East Asian countries like Borneo, Siam and Cambodia.
The word ‘Agastya’ might have been a title. Several Agastyas may have been involved in these stories, syncretised into one.
An Agastyāśrama, a hermitage of Agastya, has been mentioned in the Rāmāyaṇa. This has been sometimes identified with Agastyapurī, east of Nasik in Maharashtra state.
The Vanaparva of Mahābhārata (88.13) mentions an Agastyatīrtha in the Pāṇḍya country as an important place of pilgrimage.
Seeing the star Agastya or Canopus when the sun is in the middle of Kanyā or Virgo and worshipping him at night is mentioned as a vrata (religious rite).