^ I loved it when, in MJF's TNG/X-Men team-up "Planet X", Picard "meets" Xavier in the holo-deck and notices the resemblace! One of the most unintentionally funny moments in all of Trek Lit.
What makes you think it was unintentional?
And yes, it did predate the movies, as did Diane Duane's X-Men novel in which she distinctly wrote Xavier with Patrick Stewart's speech patterns (I think he even said "Make it so" at one point). I think everyone in the world who was a fan of both TNG and the X-Men had pegged Patrick Stewart as the ideal Xavier all along. I know I first had the idea over a dozen years ago. (And Bryan Singer is a big Trek fan, after all.)