Camelot 3000 - Mike W. Barr

In the year 3000, an armada of destructive aliens has unleashed an all-out assault on Earth and is poised to conquer the planet. But when a young boy stumbles upon the crypt of King Arthur, the legendary monarch and the Knights of the Round Table are magically reincarnated.
Together once again, King Arthur, Sir Lancelot, Merlin, and the rest of the classic knights take on the invading extraterrestrials and their wicked leader, Morgan Le Fay, the half-sister of Arthur. A mythical tale of honor and bravery, CAMELOT 3000 proves that some heroes are timeless.