A venomous and powerful snake. He was born to Kashyapa and Kadru.

Once he cheated Narada, who banished him to a forest and cursed that he would stay there immobile until Nala released him. So Karkodaka remained there waiting for Nala. Once, there was a forest fire and he began crying for help, calling for Nala. This was when Nala was roaming in the forest after leaving Damayanti. Nala heard the cries and Karkodaka then informed him of Narada’s curse. Karkodaka reduced his size and Nala carried him to a safe place. Karkodaka then asked Nala to walk ahead counting his steps. At the tenth step, Karkodaka bit him and disfigured him. He said that he had done so, so that Nala wouldn’t be recognised and also informed him that Kali, who had caused Nala’s downfall, was living inside him and the venom had affected him. Nala would henceforth be immune to venom and would be invincible in wars. Karkodaka advised Nala to take on the name of Bahuka and become the charioteer of the king Rituparna of Ayodhya and said that they would teach other Ashwahridaya and Akshahridaya mantras. Karkodaka then gave Nala two dresses and said that he would would regain his normal form when he wore them. Karkodaka blessed Nala before leaving as per Mahabharata Vanaparva Chapter 66.