Brian Leslie Weiss (born November 6, 1944) is an American psychiatrist, hypnotherapist, and author who specializes in past life regression. His writings include reincarnation, past life regression, future life progression, and survival of the soul after death.

As a traditional psychotherapist, Dr. Weiss was astonished and skeptical when one of his patients began recalling past-life traumas that seemed to hold the key to her recurring nightmares and anxiety attacks. His skepticism was eroded, however, when she began to channel messages from "the space between lives," which contained remarkable revelations about Dr. Weiss's family and his dead son. Using past-life therapy, he was able to cure the patient and embark on a new, more meaningful phase of his own career.

A graduate of Columbia University and Yale Medical School, Brian L. Weiss M.D. is Chairman Emeritus of Psychiatry at the Mount Sinai Medical Center in Miami. Dr. Weiss maintains a private practice in Miami.