Real creatures: Tiger

"Other kind of real" creatures:
Ooh this made me go YES that's the one when I was looking around. The Grim Reaper. I'll save that for the non-animal thread when it comes. It doesn't get much more gray and neutral than that honestly. Even has immortality wrapped about it. It's perfect in so many ways.

Considering it has to be an animal-esque creature
I would consider a Storm/Water dragon mostly.
Otherwise Sphinx.

For shits 'n giggles: Nessie from scotland :3