Matsyendranath (sometimes transliterated Machindranath) (9th-10th century) was one of the eighty-four Mahasiddhas, and is the patron deity of Nepal. He was guru of Gorakshanath, with whom he founded the school of Hatha yoga, one of the branches of Yogic practices.
Matsyendranath was born out of fish's womb and then adopted by a fisherman. He is considered by many to be the founder of the Nath Sampradaya of sadhus. While the Naths had actually been known much earlier, from the time of Dattatreya, Matsyendranath did initiate a revival by combining the three viewpoints of Siddha, Tantra, and Nath philosophy.
He is venerated as a Mahasiddha in Vajrayana.
Machhindranath temples in Nepal:
Amongst the most famous temples of Machhindranath in Kathmandu valley, one is Rato (red) Machhindranath temple in Patan and the other one is Seto (white) Machhindranath temple in Kathmandu.
Photo By me.