Mahavatar Babaji is the name given to an Indian saint and yogi by Lahiri Mahasaya and several of his disciples, who reported meeting him between 1861 and 1935. Some of these meetings were described by Pramahansa Yogananda in his book Autobiography of a Yogi, including a first hand report of Yogananda's own meeting with the yogi. Another first hand account was given by Yukteswar Giri in his book The Holy Science. According to Sri M's autobiography (Apprenticed to a Himalayan Master) Babaji, was Shiva. In the second last chapter of his book, he mentions Babaji changing his form to that of Shiva. All of these accounts, along with additional reported meetings, are described in various biographies. According to Yogananda's autobiography, Babaji has resided for at least hundreds of years in the remote Himalayan regions of India, seen in person by only a small number of disciples and others.
Again, according to his autobiography, shortly before Yogananda left for America in 1920, Babaji came to his home in Calcutta, where the young monk sat deeply praying for divine assurance regarding the mission he was about to undertake. Babaji said to him: "Follow the behest of your guru and go to America. Fear not; you shall be protected. You are the one I have chosen to spread the message of Kriya Yoga in the West."