NUTRIA! In terms of a common critter taking bullets & continuing to live, in my experience only, a nutria is one tough critter........solid bone, muscle, pea brain, covered with thick wet fur.
As for other critters, a wolverine is one mean critter that can also absorb lead. My dad had one attack him in the 60s at close range........so close his scope was a hindrance. He hit the thing repeatedly in the non-vitals with a .308 Model 88 Winchester, 7 times........guts blown all over the place, he just couldn't get a round into the right place apparently. 7th shot knocked the thing down and rolled it over a log; he thought that did it. Then it got back up, crawled over the log with blood foaming from its mouth, dragging everything with it, stared at him, then come at him again. He made a dead run for his car over a mile away and never looked back...saved his last round in his last mag just in case. I've never seen a wolverine, and he had never seen one prior to, or since then, but that episode sure made me a believer in the stories about them being tough and mean.
RR