The robotic Sentinels may not have their own conciousness, but despite being used as a pawn against the X-Men over the years, they remain among their most iconic villains. Now admittedly somewhat less effective due to overexposure (meaning that they're no longer as frightening a concept as they once were), these robots still represent everything that's wrong with humanity and their prejudices against the mutant race. The X-Men have taken on so many powerful threats that pitting them against the Sentinels may seem almost like an unfair fight to the robots these days, but there are plenty of great examples of the team being pushed to their limit as they've been surrounded by these sometimes skyscraper sized menaces who can wipe them out with a single blast. Look no further than the Days of Future Past comic for proof of that!
