(CBR) "X-Men: Days of Future Past" has ushered Marvel's mutants back into the spotlight in a big way. The film has won over critics and fans alike, proving that there's still plenty of life left in the fourteen year old franchise.

And in addition to bidding a fond farewell to some of the actors who built the franchise up over the years, the overall series feels young and fresh, thanks in part to the new blood that appears in the timeline-jumping reboot, with fan favorite comic book characters like Bishop, Quicksilver, Warpath, Sunspot and Blink all made their debut in the latest installment. All five of those new movie X-Men have been around in the comics for a long time; the newest -- Blink -- debuted in 1994, while the oldest -- Quicksilver -- got up and running fifty years ago.

And yet, even with these new entrants into the X-Men's movie-verse, there are still classic characters who have yet to have had even a passing cameo. All five original X-Men have appeared, of course, and so has every member of Chris Claremont and John Byrne's international lineup. But which mutants have fallen through the cracks? Which X-Men have been around the longest in the comics and still haven't made their way to the big screen? Here are five classic X-Men we have to see in 2016's "X-Men: Apocalypse."

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