Shri Matsyendranath (c. 1000 C.E.) was the son of Minanath, a fisherman. He is considered by many to be the founder of the Nath Order of sadhus. While the Naths had actually been known much earlier, he did initiate a revival by combining the three viewpoints of Siddha, Tantric, and Nath philosophy.

References
Mahendranath, Shri Gurudev. Ecstasy, Equipoise, and Eternity.