That Nation of Islam (warmonger, attacks without declaring, forces smaller nations to become his vassals just so he can become stronger, and then he backstabs them): https://www.warlight.net/Profile?p=8753909112
Aaron Lloyd Emerson (though he does follow rules, he's not very compliant. We all asked him to surrender, rather than VTE in a diplo we were playing because we were going to surrender for the lowest level, but he refused. we had to beat him into submission. more of a personal reason I suppose, but here's the link anyway): ://www.warlight.net/Profile?p=8655736768
And then of course, Remove Kebab. He joins diplos (he even said this himself) just to break the rules and ruin them for everyone else (he's in 114 of them right now, I'd like that number to go down). link: https://www.warlight.net/Profile?p=7766589534
Just a few more you should probably add.