LIghtsaber vs. Superman
At least the fight would have a cool soundtrack, what with John Williams on both sides.
I'm no expert on Superman canon (maybe Dave T will weigh in), but if lasers can hurt Superman, then a lightsaber should be able to hurt him. But to do serious damage like lop off an arm, it would have to be wielded by someone very strong.
And a kryptonite lightsaber? That's brilliant but cheating. Who would build a kryptonite lightsaber? Well, besides Batman. He's working on one right now.