January - Sneasel
My favorite cold-climate organism is Pyrrharctia isabella, the Isabella tiger moth - more specifically, its larval form, the woolly bear caterpillar. Wooll bears show up all over temperate and colder regions. They normally pupate in the same season as they hatch, but those unlucky enough to be born in the arctic can only feed so long before the rapid onset of winter leads to freezing. Natural antifreeze agents in their blood allow them to hibernate until they thaw the next year and continue eating - sometimes taking over a decade to reach maturity.