He is Ganesh-svarupa.

One of the Nava-naths (the nine Great Naths).

When Parvati had a son Ganesha, all the gods came to greet him, but it was the greatness of Shiva Adinath that captivated Ganesha, and he asked to give him the form of nath. To what Adinath answered that Ganesha will definitely become a yogi, incarnating on Earth, where he will be called Gajabeli Gajakantharnath, and he will be addressed to the first prayers while worshiping other gods. He predicted that Ganesha would gain great knowledge, after which he would spread nath-yoga that leads to moksha. After this, Ganesha committed many acts, of which we know from the puranas: he went around the earth, competing with his brother for the leadership; married Riddhi and Siddhi; he took the Atma-lingam from Ravana; recorded the "Mahabharata". Once Guru Gorakhnath, performing yatra on all the worlds, visited Ganesha-loka and gave initiation to the god Ganesha. Then, turning into a yogi, at the request of Gorakshanath, Ganesha went to Earth, where he gave himself up to severe tapas, and later became a great patron of yoga and a carrier of yogic knowledge.

Based on: Magazine "Adesh" #2 "Nine Great Yogis"