7. Kor-El
Despite the fact that Superman is supposed to be the last surviving Krytonian int he galaxy, according to his origin story at least, over the years there have been enough of his fellow alien-kind to populate a small town. Ignoring Supergirl and Zod, it seems that any time writers want to add a bit of special interest to a Superman story, they have someone appear who also survived the death of his planet (somehow,) including one memorable World's Finest story in which Thomas Ellison (Bruce Wayne's slightly deranged babysitter) convinces Bruce he's actually from Krypton as well. Anyway, the other worst example comes from World's Finest #246-247, which tells the story of Kor-El, Superman's supposedly long-lost, deformed brother, who Superman exiled in space. This upsets the world, including Batman, who is outrages, and when Supes frees his brother, it becomes clear why the exile happened (Superman handily wiped his own memory to stop familial guilt inspiring a reckless rescue attempt) as Kor-El becomes dictator of Earth. It turns out Kor-El is actually just Parasite in a sneaky disguise, who managed to discredit Superman as a brother-hating bigot.
Why He'd Suck This is one of those stories that could be adapted to bring Batman to Metropolis, if Snyder and co decide to take a more fluid adaptation of The Dark Knight Returns (i.e. stomping all over it and taking out one tiny detail to extrapolate into a whole story, as modern adapters seem to like doing.) But it would be a terrible decision - there's been no hint that Superman had a brother, plus the idea of him being deformed, from a "perfect" planet would be odd, and if this was how anyone suggested introducing a villain as good as Parasite, they should have their toes cut off.