X-Men (1992) - Season 5, Episode 76
It's the final episode! At a Mutant/Human Relations Summit, Henry Peter Gyrich attacks and severely injures Professor Xavier with an energy disruptor. Meanwhile Magneto makes final preparations to take over the world with his mutant army, but on the eve of the invasion Cyclops, Wolverine, and Jean Grey infiltrate Genosha to tell Magneto that Xavier is dying. Magneto halts his plants out of respect to his long-time friend and joins the X-Men as they say farewell to their beloved mentor.