Reincarnation

Reincarnation was a religious belief. The Aztecs believed Barbara Wright to be a reincarnation of Yetaxa. (DW: The Aztecs)

After his encounter with The Book of the Old Time, the Seventh Doctor began to suspect that before regeneration, there had been reincarnation. (NA: Cat's Cradle: Time's Crucible) The Doctor later discovered that he may have been the reincarnation of the Other. (NA: Lungbarrow)