In the Marvel universe, crossovers are pretty common most especially in the comics. However, as for the movies or the cinematic universe, Marvel and Disney are the first ones to ever make a crossover in the MCU.

As for Fox, director, Bryan Singer, has recently teased fans that they are now planning to make a crossover for the "X-Men" franchise and the new "Fantastic Four."

While speaking with Yahoo Movies, Singer revealed to fans of the film that they are now thinking about the idea of a crossover between the two franchises.

"Those ideas are in play, that would be a natural match-up because they're both ensemble films and there is a natural mechanism by which to do it," Singer told Yahoo Movies during his interview for the "X-Men: Days of Future Past – The Rogue Cut."

But of course, the director still has to make sure how the standalone movies will turn out, particularly the upcoming "Fantastic Four" movie reboot.

Singer added via Variety that "we have to see how the films turn out — how this film turns out, how 'Fantastic Four' plays, to really understand what kind of desire and how that would really work. I think to just say you're gonna do it is a mistake. You have to see how the films evolve before you make the decision to completely commit to that."

Sadly, the director declined to give out further details on how it will happen and when. However, the director did drop a very subtle hint on what fans can expect. He said, "It deals with time. That's all I'm going to say."

If time is going to be the core of the crossover, Singer is pretty much the ideal person to take the lead for this film, most especially because of how great the 2014 "X-Men: Days of Future Past" movie turned out.

The "Fantastic Four" reboot is set to premiere in theaters on Aug. 7, 2015.