The End's parrot (Metal Gear Solid 3 )
If this boss battle hadn't have been so ridiculously tedious, the parrot would still be alive today. As our patience waned from endlessly tracking the decrepit old fool, our attention was directed towards his loyal bird and whether he could be shot. Like a dirty savage, after putting a bullet through his beak Snake devours it and then continues with the job in hand.
As with all of these moments of unnecessary carnage, there's a downside. In this case, it's that the parrot can be used to reveal The End's position. If you manage to capture it alive and then set it free again, birdie will fly around its owner making it easier to identify his location.
Above: This parrot is dead. No, it's just sleeping. Actually, it is dead, because I shot it and then ate its warm little body