Ever since the first X-Men film, there have been calls from the fans to show the Sentinels. An early draft of the original film did include Sentinels. Sentinels were set to appear in the sequel, but were deleted due to budget concerns. A Sentinel did finally appear in the Danger Room in X-Men: The Last Stand, but only as a silhouette and severed head. The Sentinels are the key villain in the Days of Future Past storyline. They control America and many are fought and destroyed by the X-Men. Days of Future Past must show the Sentinels in all of their malevolent metallic mutant-hunting glory.