In paleontology, a Lazarus taxon is a taxon that disappears for one or more periods from the fossil record, only to appear again later. Likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered. The term Lazarus taxon was coined by Karl W. Flessa and David Jablonski in 1983 and was then expanded by Jablonski in 1986. Paul Wignall and Michael Benton defined Lazarus taxa as, "At times of biotic crisis many taxa go extinct, but others only temporarily disappeared from the fossil record, often for intervals measured in millions of years, before reappearing unchanged". Earlier work also supports the concept though without using the name Lazarus taxon, like work by Christopher R. C. Paul.

Lazarus of Bethany is a figure within the Christian Bible, mentioned in the New Testament in the Gospel of John, who four days after his death is restored to life by Jesus. This is seen by Christians as one of the miracles of Jesus. In the Eastern Orthodox Church, Lazarus is venerated as Righteous Lazarus, the Four-Days Dead. The Eastern Orthodox and Catholic traditions offer varying accounts of the later events of his life.