X-Men: Apocalypse marks the first time that James McAvoy portrays a traditional Charles Xavier (i.e., wheelchair-bound professor, at full psychic power, running the X-Mansion as a School For The Gifted) during his three film stint in the franchise -- having previously appeared as a still-walking version in X-Men First Class and a version who could walk or use powers but not at the same time in Days of Future Past. But when the film opens, he has yet to sport the character's iconic bald dome.
That change will come later and require a shave -- which director Bryan Singer helpfully shared with onetime Professor X, Patrick Stewart.
Thanks to FaceTime, Stewart was able to watch and joke with his younger "self" as McAvoy lost his mane to complete his transition into the version of Professor X most familiar to comic readers and memorably portrayed by Stewart in the majority of the previous X-Men films. While McAvoy joked that he was now beginning to feel a true connection to the famously bald-headed older actor, Stewart was quick to point out that he has been bald since he was 19 -- several years younger than McAvoy is now.
The film, which takes place in a version of the 1980s continuing from the alternate timeline created by the events of Days of Future Past, provides an explanation as to why Xavier went bald. However, the plot primarily concerns a scheme to conquer the world by Apocalypse (Oscar Isaac), an ancient being believed to be the first mutant on Earth who has returned to reclaim dominion over civilization -- conscripting Magneto, Angel, Storm, and new mutant Psylocke as his Four Horsemen servants.
McAvoy will likely be looking to get comfortable going hairless: While the next official installment of the main X-Men franchise has yet to be announced, his Xavier has been confirmed to appear as part of the spin-off New Mutants. It's also possible that he could appear as part of Deadpool 2 or X-Force, both of which are on Fox's fast-track list after the first Deadpool became an unexpected smash hit earlier this year.
As Deadpool remains the only recent X-Men film to depict the present-day world in it's new timeline, it's unclear whether the "present" Professor is still set to resemble Stewart or merely an older McAvoy. Stewart has been signed to make at least one more appearance as Xavier in Wolverine 3, which will take place in the future and may be inspired by the comic series 'Old Man Logan' -- which featured an elderly Wolverine living in a dystopian far-future world.
X-Men: Apocalypse will open in U.S. theaters on May 27, 2016, followed by Wolverine 3 on March 3, 2017, and unannounced X-Men films on October 6, 2017 (possibly Gambit), January 12, 2018 (possibly Deadpool 2), and July 13, 2018 (possibly The New Mutants).