"Megafauna" is often treated as an informal term, but this list follows the criteria outlined by Paul S. Martin. List consists of animal species weighing a minimum of 40 kilograms (90 lb.) (Martin, 1984; Martin et al., 1999). Species whose average mass typically is lower than 40 kg but still have recurring documentation of exceptionally massive individuals are included, even if such massive individuals have not been seen in recent decades. Animals generally considered "large" but have a smaller mass are excluded. This list is incomplete and is subject to revisions.

Though all organisms are significant, megafauna are an unexpendable component of Earth's ecosystems and their health and well-being is reflective of the ecosystem's health. "Megafauna" has adopted a somewhat negative-association among environmentalists who sneer at the inflated "charismatic megafauna", but the reality is that most megafauna are obscure, poorly studied, or less charismatic than some smaller animal species.

This list only accepts taxa that are species or lower