As new details emerge about the plot of the latest X-Men film, Dark Phoenix, one of the major revelations seen throughout the first trailer is that Professor Charles Xavier, despite all his noble intentions, may be the true antagonist of the entire film franchise. Though he intends to bring about a harmonious society of mutants coexisting peacefully with humans, Xavier pursues this goal with questionable methodology and a single-minded drive that throws caution to the wind and puts others in very real danger.
The concept of Xavier being a less-than-altruistic, reckless figure is not a new one, nor is it one present exclusively in the films. The entire initial premise behind Marvel's Merry Mutants is that Xavier recruits and deploys children to further his agenda. They eventually age into adults, they possess incredible superpowers, and it's ultimately a noble cause, yes, but putting children deliberately in harm's way, occasionally against literal murder machines, is hard one to defend morally.
The moral ambiguity of this strategy was largely explored in the 2006 miniseries X-Men: Deadly Genesis written by Ed Brubaker and illustrated by Trevor Hairsine. The comic revealed that Xavier had recruited a secret X-Men team led by Vulcan, Cyclops' long-lost brother Gabriel Summers, to rescue the original team after they were held captive by the living island Krakoa. After the disastrous mission results in the apparent deaths of the entire team, Xavier erases Cyclops' memory of their existence before recruiting the iconic all-new, all-different squad introduced in the pages of 1975's Giant-Size X-Men #1 by Len Wein and Dave Cockrum.
While the cinematic incarnation of Xavier has yet to do anything quite this nefarious, his calculated and repeated mental intrusions of Jean Grey seen in 2006's X-Men: The Last Stand and Dark Phoenix put the X-Men founder in a very questionable position. Sensing the dark, destructive potential within the teenage Jean Grey, Xavier placed telepathic mental blocks on her mind in order to contain the malevolent persona within. This leads to the Phoenix emerging more violently than ever in both films wrecking widespread destruction and loss of life including Xavier himself in The Last Stand.