The mutant-hunting robots in X-Men: Days of Future Past are called Sentinels.
Sentinels are artificial machines created to identify and combat mutants. In the film’s future timeline, they have become an overwhelming threat to mutants and humans who carry the potential for mutant descendants. Their adaptive abilities allow them to copy or counter mutant powers, making them especially dangerous opponents.
The movie also depicts an earlier generation of Sentinels developed in the 1970s. These machines are larger and less adaptive than the later models, but their deployment becomes central to the political crisis involving Bolivar Trask and the U.S. government. In Marvel Comics, Sentinels are among the X-Men’s most recognizable recurring enemies. They are sometimes confused with the Reavers, cyborg mercenaries associated with Wolverine stories, or the Purifiers, an anti-mutant human group.