Dr Timothy Leary (October 22, 1920 - May 31, 1996) was American psychonaut, Harvard psychologist, philosopher, author and teacher. He was prominent in the 1960s and 1970s in particular, as a proponent of the use of psychedelic drugs such as LSD.

During the 1960s, he coined and popularized the catch phrase "Turn on, tune in, drop out."

He worked closely with Dr Ralph Metzner and Dr. Richard Alpert (later known as Ram Dass).