Despite his very convincing costume, this is actually a human being. He went trick-or-treating as a yeti on Halloween, but found that he could not get out of it. What's more, his mask muffled his voice, making his cries for help sound like beastly growling. He was captured by an animal rights group, who shipped him off to the arctic, thinking that he was from that area.
The man managed to tear a mouth hole in his costume to eat, and has lived by strangling penguins for food. He tried fishing, but could not find any wood or string to make a fishing rod with, and the water was too cold for him to try catching them with his hands.
His suit is thankfully quite well insulated, so he doesn't need to worry much about the biting cold, but he has enough sense to know that if he got wet, he would freeze to death.
He lives in an igloo for warmth.

This took me about 4 hours to make: the fur effect was quite difficult to get just right