Late Quaternary prehistoric birds are avian taxa that became extinct during the Late Quaternary – the Late Pleistocene or Early Holocene – and before recorded history, specifically before they could be studied alive by ornithological science. They had died out before the period of global scientific exploration that started in the late 15th century. In other words, this list deals with avian extinctions between 40,000 BC and AD 1500. For the purposes of this article, a "bird" is any member of the clade Neornithes, that is, any descendant of the most recent common ancestor of all currently living birds.
The birds are known from their remains, which are subfossil; as the remains are not completely fossilized, they may yield organic material for molecular analyses to provide additional clues for resolving their taxonomic affiliations. Some birds are also known from folk memory, as in the case of Haast's eagle in New Zealand.