11. Doctor Fate
Superman doesn't have many weaknesses, but he's notoriously susceptible to magic, making David Blaine a serious contender for this list too. Obviously mere conjurors need not apply though, as a certain power base needs to be present as a bare minimum to even be considered a real threat.
Step forward DC's most compelling magical character, Doctor Fate, a hieroglyph throwing magician billed as one of the most powerful sorcerors in the known universe. That's almost overkill when it comes to facing a character with a known weakness to spells.
And it's not just about magic either - Superman can overcome magical opponents by crippling their ability to do spells, after all - because Fate also boasts flight, super-strength, invulnerability, telekinesis, telepathy, pyrokinesis and the ability to manipulate lightning. He's already a superman himself before he starts throwing spells into the mix.