Grey wolf

This beautiful animal has had a contentious relationship with humans, who hunted it nearly out of existence, for generations. Conservationists have fought—and fought hard—to bring its 300 survivors of continuous purges back up, although grey wolf numbers will likely never reach their peak of over 2 million.

Still, there is some reason for optimism; a 2013 species count found nearly 4,500 wolves living in the Lower 48—including in Yellowstone National Park. But efforts to restore and maintain them continue.