A caterpillar, of course! Yes, it sounds lame, but caterpillars are quiet, and don't need much care. Some of you are saying you'd like a wolf, but really, you don't. Their nearly impossible to tame, and they're afraid of humans, so, if you want to play with it, you have to find it, and risk getting bitten or scratched.
To take care of a wolf, you would half to provide fresh carcus twice everyday, a big jug of water, a seperate room, and possibly a security camera to make sure it doesn't try to escape. Plus, its just cruel to confine an animal at that level of intelligience.
On the other hand, to take care of a catterpillar, you need to provide an aquarium by a window, Fresh leaves and a small dish of water once every 3-7 days!