Terence McKenna (November 16, 1946 – April 3, 2000) was an American ethnobotanist, mystic, psychonaut, lecturer, author, and an advocate for the responsible use of naturally occurring psychedelic plants. He spoke and wrote about a variety of subjects, including visionary experiences, plant-based entheogens, shamanism, metaphysics, alchemy, language, philosophy, culture, technology, environmentalism, and the theoretical origins of human consciousness.