Metal Gear Solid V: The Phantom Pain - Every Screenshot You Need To See

Found on one of your first missions out in the field, you'll come across this tiny wolf, who you can then raise and train to take back out in future missions.

Named 'Diamond Dog' after your unit, he can actually die under the right circumstances, but the very idea of training a killer wolf who's got your back in the middle of a firefight is easily one of the coolest new aspects of the game.