Superman vs. T-1000:
Superman freezes it with his super breath and then vaporizes it with heat vision.
Superman vs. Predator:
Superman is invulnerable to all of the Predators weapons, and the Predator doesn't know about kryptonite, so Superman squishes Predator like a bug
Superman vs. Alien:
Superman is impervious to acidic blood, and squishes Alien like a bug, Superman is also able to fend off face huggers with ease.
Superman vs. The Borg:
It takes awhile, but he kills them all, the Borg nanites cannot assimilate the Kryptonian physiology
Superman vs. Honey Boo Boo:
Superman's head explodes when he realizes he has saved the human race countless times and this is the result