The birth of Parashurama, sixth avatar of Vishnu — a sage-warrior who wields an axe (parashu) gifted by Shiva, and who appears in both the Ramayana and Mahabharata as a bridge between the two epics' eras.
वैशाख शुक्ल तृतीया
Parashurama is traditionally held to have reclaimed the coastal land of Kerala and the Konkan from the sea, and in the Mahabharata's backstory, to have trained both Bhishma and Karna in warfare — tying him directly into both epics.
Observed more quietly than other avatar jayantis, mainly through temple visits and readings of his story, particularly in coastal Maharashtra, Kerala, and among communities who trace their lineage to him.