Marlin 1894c in .357 and a decent S&W revolver to go with it. Mutual ammunition, can be used with .38 Special or +P ammunition for training or smaller game. Packable, not as much as a breakdown rifle but it's pretty short (18.5" barrel) and not so heavy (6 lbs unloaded).

If you can't defend yourself with 9 rounds in the rifle and 6 in the revolver, you might as well give up.

If you're looking for more of a very small game, plinking type of rifle, the aforementioned Ruger 10/22 has to be about the best choice available. Small, lightweight, folding stock available depending on your location, enough other accessories and upgrades to make an AR shooter cry and the ammunition is the most widely available anywhere in the U.S. For defense purposes it's not ideal but then again, you can put 10 hollowpoints out the muzzle pretty damned quickly if you have to. You might not stop someone with 1 round but I sure wouldn't want to get hit by all 10.