Patrick Stewart might have just let X-Men: Apocalypse's biggest secret slip during an interview this week.

'X-Men: Apocalypse' Set To Be Biggest In Franchise's History 

For months now fans have been under the impression that Stewart (Charles Xavier) and Ian McKellen (Magneto) will not be reprising their roles in the upcoming Marvel flick. However, on Feb. 6 Stewart revealed a rather surprising piece of casting news during an interview with Oregon Live.

The actor insisted that McKellen is "certainly going to be in" the upcoming movie, meaning that the original Magneto and his past self (played by Michael Fassbender) might just be meeting up for the first time onscreen.

New Timeline Might Mean Major Changes For 'X-Men: Apocalypse' 

As for Stewart's involvement with the project, the actor insisted that he won't be returning to the franchise this time around. "I understand that it seems to be very unlikely that I will be in the next X-Men movie, which is almost getting ready to start shooting," explained Stewart, who added that he will be appearing in the upcoming Wolverine project. He will star in the picture alongside Hugh Jackman, who is still unconfirmed for X-Men: Apocalypse.

McKellen's return could mean that the new movie, set in the 1980s, could be playing around with the past and present as it did with X-Men: Days of Future Past last year.

Other returning stars for X-Men: Apocalypse will include James McAvoy as the young Charles Xavier, Evan Peters as Quicksilver, Rose Byrne as Moira MacTaggert and Jennifer Lawrence as Mystique.

Game of Thrones star Sophie Turner will be making her debut in the franchise as a young Jean Grey, with Tye Sheridan (Mud) coming on board as Cyclops and Alexandra Shipp (Aaliaya: The Princess Of R&B) stepping into the role of Storm.

X-Men: Apocalypse is scheduled to hit theatres May 27, 2016.

Tags: X-Men Marvel Movies