From the moment man invented machine, man has been putting machine against machine. OK, that's not entirely true -- depending on how loosely you want to define "robot," it seems clear that the first automatrons were gentle things programmed purely to delight ... or golems designed to smash. It's hard to decide where the line of definition falls.
But, I can say with certainty that the first time "robot" appeared in print was in Karel Capek's 1920 play R.U.R. (Rossum's Universal Robots). Naturally, it involved robots being invented, learning about violence, and rebelling against their human makers as almost all robots stories do. Perhaps it might be more accurate to say man invents machine, and machine just starts smashing whatever it feels like, be it human or metalkind?
At any rate, the "Robot, smash!" genre is alive and well, and judging from Transformers and the upcoming Real Steel, capable of spinning complex and perpetuating mythologies. It seems that the only thing more enjoyable than watching people fight one another in the 21st century is watching robots fight one another.
It's time to start documenting and ranking this decidedly futuristic genre. And so, without further ado, here's the best movies that feature robots pummeling one another into scrap metal.
1. Terminator 2: Judgment Day
There are certainly bigger robot fighting movies, but in my opinion there's none better than Terminator 2. There's just so much packed in! Can history be changed? Can a machine learn to love? Does new technology always fail due to its maker's overconfidence? Is humanity doomed because of its reliance on that technology? Good stuff all around, and still quite terrifying. Other Terminator installments also featured Skynet warriors dueling it out -- The Sarah Connor Chronicles must have had one an episode! -- but all of them played as pale imitations (right down to the lines spoken) of T2.
I can't say I enjoyed it, but many, many people did. (It's how we ended up with two subsequent films, after all.) I hesitate to use "elegant" and "Michael Bay" in the same sentence, but there's no doubt the first Transformers really was that very thing, especially in comparison to the CG orgy that followed. This is the robot-versus-robot film for those who found T2 too morally ambiguous, and simply needed to see giant shiny automatons hit one another. Oh, and Megan Fox.
3. Iron Man
Technically, Iron Man is not a robot. He is just a fancy exoskeleton. But are you really going to deny the fight between Iron Monger and Iron Man a spot on this list when either one could flatten you into the texture of raspberry jam? I thought not. Besides, it's a pretty spectacular mechanical smashfest, and so dang loud that it's easy to forget there are men inside the metal. (See also: District 9, Avatar, and Iron Man 2.)
4. Blade Runner
If Deckard is truly a Replicant (which is not an interpretation I'll ever believe, but your mileage may vary) then the fight between he and Batty is one of the most elegant and old-school robot fights of all time. But if Deckard isn't a Replicant, than it's just a good (and nearly fatal for Rick) throwdown between a human and a desperate, dying machine. Which is it? I don't know, so I'm going to put it here at #4, just to hedge my bets.
5. The Star Wars Prequels
If Transformers is too much for you, but you crave robots shooting other robots, than you're in luck! George Lucas made three of them! Theoretically, there are humans in this movie, but I just remember lots and lots of spindly robotic troops blasting at one another. If you're angry at your toaster, laptop, iPhone, or XBOX, this might be just the thing to loop in the background as a relaxing screensaver. (I, Robot and A.I.: Artificial Intelligence may also fulfill these needs since it features robots destroying one another, but in a mindless, assembly-line kind of way.)
6. Robot Jox
Before there was Michael Bay and Shawn Levy cooking up their robo-mythos, there was Robot Jox, which dared to imagine a world where wars were outlawed, and superpowers settle disputes by fighting large mechs against one another. Achilles, the Peter Gallagher lookalike, has the heavy task of defending America and Alaska from Alexander and his Russian operator. It's a beloved memory for many a '90s child who needed to fill the time between Power Rangers episodes.
7. Robocop 2
I feel odd putting this below Robot Jox because it is equally bad, but if the Internet is any indication, Robot Jox has a bigger and more enthusiastic fanbase than Robocop 2 does. But for one dark year in the 1990s, those needing a live-action robo-battle had no choice but to watch the final battle between Robocop and Robo-Cain. Afterwards, they would talk feverishly about how much better it would have been if Frank Miller's original script had been filmed. A year later, T2 came out, and those people wondered why the heck they had watched those stop-motion robocops so eagerly. And then Miller published his Robocop 2 script and ... well, we'll just stop there. This entire entry just feels shameful now.