Peter Felix Barth (also known as Lama Thapkhay) (born 1956) is an American writer specializing in the mind teachings of Tibetan Buddhism.

[1] In statistical mechanics, he was responsible for an exact solution to the Ising model for highly-branched, closed-Cayley trees, an area of interest in neurophysics and neural networks.

[2] He has a background in neurophysics, engineering and education, having served as adjunct professor in Information Systems Management (ISM) at the University of San Francisco.

[2] While in India, Barth had studied Mahamudra under a number of Drukpa Kagyu lamas, including Dukchen Thuksey Rinpoche in Darjeeling, who personally played a role in the preservation of Dakpo Tashi Namgyal's text, Moonbeams of Mahamudra, when he requested Lobsang P. Lhalungpa translate it into English and noted that, "This is the most important sacred text!

"[14][15] Barth's first book, Piercing the Autumn Sky: Discovering the Natural Freedom of Mind, was inspired by this work and the oral instructions on it by Thrangu Rinpoche in 1989, as translated "on the fly" by Ken McLeod.

[27] Since 1998, he has been listed as "Lama Thapkhay" (at Mahamudra Meditation Center, Petaluma, California)[28] on the official website of the 17th Karmapa, Ogyen Trinley Dorje.