10. X-Men: Days Of Future Past
The X-Men films have had a difficult story to follow and understand ever since X-Men Origins: Wolverine hit cinema screens in 2009 and caused vast continuity errors in the series.
X-Men: Days of Future Past came along in 2014 with the hope of amending and revising some of these mistakes by altering the timeline. It merged the old cast led by Patrick Stewart as Charles Xavier and Ian McKellen as Magneto with the new one led by James McAvoy and Michael Fassbender as those same characters.
It did this through the use of time travel, with Wolverine being tasked with changing the past, due to his regenerative abilities making him the perfect candidate to send back in time and survive the trip.
The film opens in the bleak dystopian future where Sentinels are programmed to exterminate mutants and ends in the past with Wolverine waking up in the X-Mansion to find his X-Men comrades alive and well, thereby expunging anything that happened in X-Men: The Last Stand.