The list of extinct cetaceans features the extinct genera and species of the order Cetacea. The cetaceans (whales, dolphins and porpoises) are descendants of land-living mammals, the even-toed ungulates. The earliest cetaceans were still hoofed mammals. These early cetaceans became gradually better adapted for swimming than for walking on land, finally evolving into fully marine cetaceans.
This list currently includes only fossil genera and species. However, the Atlantic population of gray whales (Eschrichtius robustus) became extinct in the 18th century, and the baiji (or Chinese river dolphin, Lipotes vexillifer) was declared "functionally extinct" after an expedition in late 2006 failed to find any in the Yangtze River.