Brian L. Weiss is an American psychiatrist and author, best known for his work in the field of past-life regression therapy. He gained widespread recognition with his book, Many Lives, Many Masters, published in 1988, which details his experiences with patients who recalled past lives during therapy sessions. Weiss combines traditional psychotherapy with spiritual concepts, exploring the idea that our souls can experience multiple lifetimes. In addition to his writing, Weiss conducts workshops and seminars worldwide, teaching others about the therapeutic benefits of past-life regression. He emphasizes the importance of understanding one's past to promote healing and personal growth. His work has inspired many to explore the connections between psychology and spirituality.