Karkotaka is one of the powerful snakes or Nagas in Hindu tradition with numerous magical powers. His parents were Sage Kashyapa and Kadru. The most popular and important part played by Karkotaka in Hindu mythology is in the story of Nala and Damayanti. The descendants of Karkotaka Naga are today settled in Rajasthan and are known as Katewa.
Legend has it that once Karkotaka had cheated Sage Narada and the angry sage cursed him that he will become immobile – he cannot move his body. The sage then predicted that he will be relieved of his curse by Nala.
Nala was the king of Nishadha kingdom and he was married to the beautiful Damayanti. But unfortunately Nala was possessed by Demon Kali and he took advantage of his weakness for gambling. Nala lost his kingdom to his brother in a game of dice.
Nala then took refuge in the forest and once happened to find Karkotaka engulfed in a wild forest fire. The snake was unable to move due to the curse of Sage Narada. Nala saved him from the forest fire and as predicted by Sage Narada he regained the movement of his body.
Karkotaka then helped Nala to recover his kingdom and this story is mentioned in the Mahabharata. Karkotaka asked Nala to walk a few steps counting his footsteps. Nala did so and at the tenth step, Karkotaka stung him and his whole body turned blue.
Karkotaka then spoke to Nala as follows:
"I have changed your appearance so that people may not recognize you. Demon Kali who is troubling you still lives within you. It is he who is affected by my poison. You need not fear danger from poison any more. You will never be defeated in battle.”
“Go and engage yourself as the charioteer of Rituparna, King of Ayodhya. You will teach him Avahrdaya mantra. In return for it he will teach you Aksahrdaya mantra.”
Here are two garments which I give you. If you put them on, you will be restored to your own shape. May you be blessed again with a happy family life." After saying this, Karkotaka vanished. (M.B. Vana Parva, Chapter 66) .
Nala was able to regain his kingdom and his wife Damayanti with the advice and help given by Karkotaka.
There are temples dedicated to Karkotaka in Rajasthan, where he is the patron deity of Katewa community. In Chikhaldara in Maharashtra there is a hill named after Karkotaka and the hill also has a famous temple dedicated to Nag Karkotaka Maharaj.