20 Most Powerful X-Men Villains Of All Time
13. Nimrod
The strength of the Sentinels is in their numbers, because they're rather during a one-on-one fight against a guy with optic blasts, super strength or metal claws. So what could make a Sentinel capable of taking down a mutant in single combat? By it being a super-powerful one along the lines of Nimrod, whose dumb name belies its deadly nature.
An extremely advanced prototype sentinel that appeared in the Days Of Future Past comics storyline, Nimrod could travel through time (which means you can't really beat him, since he could just skip back in time and change how the fight ended, like the aliens in Edge Of Tomorrow), and his systems reconfigured to adapt to each foe's fighting style.
He could rebuild himself right down to a molecular level, could not only scan mutants and metahumans from a distance but instantly now their powers and prepare for fighting them, plus he could generate force fields, shoot plasma blasts and imitate Magneto's mastery of magnetism. Why weren't all the Sentinels just like that?