<3Ciel
</3Nero
Honestly nero would kill everyone ever always, except; Boss Obama, maybe Dio (because he can stop time), and Superman, but he dosen't count because he is overly cheap.
[nerd rant] Well, there are a good few dead apostles who could take out Nero. He's pretty weak in terms of relative power, he just can outlast many people due to his chaos regeneration. There are some that could destroy every bit of him in an instant though, such as Gransburg Blackmore, El Nahat, ORT, original Roa, etc. Arc could wipe his ass out easy if she was even at half power. [/nerd rant]
But yeah, Dio Brando beats everyone, INCLUDING Superman.