Old Gray Guy
Credit: Proceedings of the Royal Society

The island of Isle Royale, located in Lake Superior, is home to three wolf packs. Scientists long thought that the wolves were an isolated group, because no other wolves could make it onto the island, but upon further study, they found that a larger, light-colored wolf had immigrated to the island by crossing an ice bridge in 1997. As he's aged, his coat has become lighter — something not normally seen in Isle Royale wolves — so researchers named him "Old Gray Guy."