Theos Casimir Bernard (December 10, 1908 – death date unknown, probably mid-September, 1947) was an accomplished American practitioner of Yoga and Tibetan Buddhism, a scholar of religion and explorer.

Theos Bernard pioneered Indian and Tibetan studies at Columbia University. He was the third American to ever set foot in Lhasa, Tibet, and the first American to be initiated into the rites of Tibetan Buddhism. He published several accounts of the theory and practice of the religions of India and Tibet, including his PhD dissertation on Hatha Yoga. He was the founder of the first Tibetan Buddhist research institute in United States, he compiled a Tibetan grammar and planned for the systematic translation of Indian and Tibetan literature into English.

Although Theos Bernard claimed that his hometown was Tombstone, Arizona, he was born in Los Angeles, California.

Theos Bernard had hoped to become an athlete while being a young man, but he suddenly suffered a serious attack of infectious rheumatism that almost killed him and made him suffer from ill-health for many months. While convalescing in the Dragoon Mountains, Arizona, he dedicated plenty of time to read books about oriental philosophy belonging to his mother. After reading that “There is infinite energy available to anyone, if you know how to obtain it. And this is part of the science of Yoga” in Lily Adams Beck’s The Story of Oriental Philosophy  [6], he became convinced that Yoga was the only discipline that could give him a solution for his health. He then started reading about Yoga eagerly and talked to everyone that knew about it or who had been in India. Some time later, “a person that has just arrived from India” met him for just one night, in which he opened to Theos Bernard a whole world of Yoga philosophy and practices, becoming his first Guru. Through the years that followed, Theos Bernard perfected his Yoga practice under the guidance by mail of that Guru.

After finishing his studies in University of Arizona he traveled to India to perfect his studies. He arrived to Calcutta around September 1936, at the end of the Monsoon season, only to find that his Guru had recently died. Then, a friend of his former Guru introduced him to a teacher, called Tantrik friend [7] by Theos Bernard, who took him under his guidance. He was a man of strong theoretical knowledge, much versed in Yoga, but not a practitioner himself. After two weeks, pleased with the knowledge that Theos Bernard demonstrated, the Tantrik teacher introduced him to another teacher with actual practicing knowledge, called Swamaji by Theos Bernard. This last teacher was in charge of initiating him into Yoga in preparation for the final goal of the Yoga practice: to awaken his Kundalini. When the initiation was completed it was decided that he should travel throughout India to familiarize himself with the people and beliefs of the country. After visiting many cities and places he finally found a great teacher whom Theos Bernard references only by his title, Maharishi, who was a former student of the first Guru that Theos Bernard had met for just one night in the USA, and that for that reason knew about Theos Bernard beforehand. It was this Maharishi that after a complete training of around three months guided Theos Bernard to awaken his Kundalini.

In order to get important Tibetan manuscripts, mainly the Kangyur  and the Tengyur , Theos Bernard traveled to Tibet. At the holy city of Lhasa he was accepted as a reincarnation of Padma Sambhava[8], a saint of the Tibetan Buddhism, a fact that enabled him to take part in many special religious ceremonies and to discuss Tibetan teachings with some of the leading lamas at famous Tibetan monasteries. He was then able to get the manuscripts he wanted and many other important books, documents and testimonies of the Tibetan Buddhism and Tibetan culture, who presently are part of a few collections in universities of the USA (see section ‘External links’). Documenting his experiences in pictures, Bernard left a historical record of an age-old civilization on the brink of political upheaval,[10] recording Tibetan civilization at the height of its development and before the Chinese invasion of 1949 and subsequent Cultural Revolution had destroyed it.

Returned from his 1936/37 trip to India and Tibet, he studied at Columbia University and earned a doctorate in philosophy. His treatise on Hatha Yoga was first published in 1944 by Columbia University Press and has since been frequently reprinted. It covers all the traditional aspects of Hatha Yoga and correlates his personal training with the major Indian texts: the Hatha Yoga Pradipika, the Gheranda Samhita, and the Yoga Sutras of Patanjali.