Sentinels

Sentinels are specialised mutant-hunting machines created by Dr Bolivar Trask as a solution to what he felt was a growing problem caused by superhuman mutants, however the Sentinels soon grew out of hand and planned on taking over humanity - ironically it was only due to the intervention the mutant superhero team known as the X-Men did the Sentinels plan for domination topple.

However the damage had been done and many other villains and misguided souls created new versions of the Sentinels - some driven by hatred of mutants, others simply trying to make the world safer - these Sentinels varied largely in size, function and danger but all of them shared a common trait: they were merciless hunters of the mutant race and a symbol of fear and hate in the eyes of many.

In addition to the legions of lesser-drones there have been a number of Sentinels who have evolved beyond their normal programming and have become super-villains in their own right, examples of these elite Sentinel units would be Master Mold (the supreme leader of the Sentinels in the early years), Nimrod (a future Sentinel of immense power) and Bastion (the mystical-fusion of Master Mold and Nimrod).

Sentinels by their very nature tend to be a specialised villain and as such they rarely appear as antagonists outside the X-Men books or related media: after all a giant mutant-hunting robot is not much of a threat unless you are indeed a mutant, however they remain one of Marvel's most iconic and popular villains and indeed even inside their setting they are both celebrated and reviled in equal amounts by varied factions.