Baiji River dolphin
Declared "functionally extinct" as recently as 2006, the Baiji River dolphin became the first cetacean to go extinct in modern times due primarily to human influence. Because of its recent extinction, however, DNA can still be easily extracted from remains. In fact, efforts to retrieve and store the animal's DNA are under way.
Like with many extinct species, however, the question remains about whether the Baiji River dolphin would have a home to return to after being resurrected. The Yangtze River system, where this dolphin was found, remains heavily polluted.