I don't have a lot of room in my brain for criticism on Brad Bird's directorial debut, The Iron Giant, because I absolutely love that movie, which is exactly why the only way I can improve it is by expanding it with a sequel. My single complaint about The Iron Giant is that I could have used more The Iron Giant.
If you haven't seen it, The Iron Giant is an amazing animated feature about an enormous, metallic robot sent to Earth from some other planet bent on ruling or otherwise destroying the world. The Giant, voiced by Vin Diesel, was originally programmed by his alien creators for war and mayhem and was, by all accounts, completely unstoppable.
"Hi, my name is John Irongiantington, and I'm made of guns!"