Senator Robert Kelly was a member of the United States Senate and a huge supporter of the Mutant Registration Act. The Brotherhood of Mutants tried to assasinate him more than once ( Days of Future Past, Dream's End), but the X-men saved him again and again. He wanted to be the President of the United States, but he died in the Dream's End crossover. A human shot him, when he made a pro-mutant speech.
Age of Apocalypse
Robert Kelly, held prisoner by Apocalypse's guards Absorbing Man and Diablo in a Mayan temple, was rescued by the X-Men Nightcrawler, Magneto, and Rogue. They were able to free him from his captors, and Kelly went on to draft the Kelly Pact, an agreement of peace between mutants and humans, though Apocalypse did not intend to keep true to the treaty.
After the fall of Apocalypse, Robert Kelly was elected President. Remembering the role the X-Men had played in destroying Apocalypse, he made a press conference telling humans across the globe to grant amnesty to the mutants that helped get human society back on its feet.
Robert Kelly was a human and did not have any mutant powers.
Robert Kelly (played by actor Bruce Davison) was featured in the X-Men movie. He was a mutant hating politician who thought mutants should be locked up for their own safety and the safety of mankind. He was a victim of Magneto's machine designed to turn humans into mutants, resulting in him becoming a jellyfish-like creature and dying.
Robert Kelly appeared in all three of the X men animated series, each time a mutant hater in a place of authority, a Senator in X men the Animated Series, later president, the Principal of Bayville High in X men Evolution and again a Senator in Wolverine and the X men. Only in the animated series was Kelly shown to eventually accept mutants (Most likely due to his later introduction to Evolution and the one season run of Wolverine)