Shri Gurudev Mahendranath (April 29, 1911–August 30, 1991) was a British mystic, writer, poet, and guru of tantra who started the spiritual organization known as the International Nath Order. Born Lawrence Miles in London, England on April 29, 1911, his interests in the area of spiritual investigation and the Pagan way of life began at an unusually early age. During his childhood, he had a number of unique experiences which began the course of his inner development and later led to his spiritual attainment and recognition by a vast public. As a young man, Shri Mahendranath met and exchanged ideas with the advanced thinker and mystic, Aleister Crowley. Personal experiences and the advice of Mr. Crowley suggested that he might gain valuable insight by the deeper study of meditation and the I Ching oracle with Indian and other Asian Masters.

After some years, Shri Mahendranath arrived in India on Guru Purnima, July 14, 1953. On this auspicious date, he was given initiation as a sannyasi into the Adinath sampradaya by H.H. Shri Sadguru Lokanath, the Avadhut of the Himalayas. He was later given Tantric initiation by Shri Pagala Baba of Ranchi into the Uttara Kaula sect of Northern Tantrics and became his successor.

During his life as a sannyasi, Shri Mahendranath traveled to Ceylon, Thailand, Bangladesh, Burma, Cambodia, Laos, Malaysia, and Australia. He also received initiations as a Bhutanese Lama, Meditation Master in Soto Zen, Taoism, and both Mahayana and Theravada Buddhism.

He founded the International Nath Order (originally Western Nath Order) to present and promote his own synthesis of the tantric teachings of the Adinath and Uttara Kaula lineages as a spiritual path for the western householder. Initiates of his International Nath Order are known as Naths.

Shri Gurudev Mahendranath left his body and achieved Mahasamadhi on August 30, 1991. His last residence was his hermitage—Shambhala Tapowan—near the Vatrak river, in the state of Gujarat, India. He was the last guru of both the Adi-Nath and Uttara Kaula tantric lineages, which became defunct with his passing.