Reincarnation, literally "to be made flesh again", is a doctrine or metaphysical belief that some essential part of a living being (in some variations only human beings) survives death to be reborn in a new body. This essential part is often referred to as the spirit or soul, the "higher" or "true" self, "divine spark", or "I". According to such beliefs, a new personality is developed during each life in the physical world, but some part of the self remains constant throughout the successive lives.

Belief in reincarnation has ancient roots. This doctrine is a central tenet within the majority of Indian religious traditions, such as Hinduism (including Yoga, Vaishnavism, and Shaivism), Jainism, and Sikhism. The idea was also entertained by some ancient Greek philosophers. Many modern Pagans also believe in reincarnation as do some New Age movements, along with followers of Spiritism, practitioners of certain African traditions, and students of esoteric philosophies such as Kabbalah, Sufism and Gnostic and Esoteric Christianity. The Buddhist concept of Rebirth although often referred to as reincarnation differs significantly from the Hindu-based traditions and New Age movements in that there is no unchanging "soul" (or eternal self) to reincarnate.

During recent decades, a significant minority of people in the West have developed a belief in reincarnation. Feature films, such as Kundun and Birth, contemporary books by authors such as Carol Bowman and Vicki Mackenzie, as well as popular songs, regularly mention reincarnation.

Some researchers, such as Professor Ian Stevenson, have explored the issue of reincarnation and published evidence of children's memories of earlier lives. Skeptics are critical of this work and say that more reincarnation research is needed.