Joseph Nicolosi (January 24, 1947 – March 8, 2017) was an American clinical psychologist, founder and director of the Thomas Aquinas Psychological Clinic in Encino, California, and a founder and president of the National Association for Research and Therapy of Homosexuality (NARTH).
Nicolosi advocated and practiced reparative therapy, a controversial practice that he claimed could help people overcome or mitigate their homosexual desires and replace them with heterosexual ones.