Nanda was the foster father of Sri Krishna and he was the
leader of the cowherds. As per the story in the Bhagavata Purana, Nanda Maharaj
in his previous birth was one of the eight vasus. Due to a curse he was born as
a cowherd. He is also known as Nanda Baba or Nandagopal or Nandagopar.
Brahma had given the boon to Nanda that he will be liberated
and return to his original abode when he will be born as a cowherd and would
take care of the ninth avatar of Bhagwan Vishnu.
According to Shiva Purana, Nanda in one of his previous
birth was a cowherd and was an ardent devotee of Shiva. Pleased with his
devotion, Shiva provided him with the opportunity to look after Sri Krishna.