Just when you think Eggman couldn't possibly get bad enough with having Tails rape Sonic and killing Klungo for no apparent reason, he then attempts to kill everybody that's his prisoner.
And then there's Tan Tao, who keeps a harem and a small personal army who kidnaps girls against their wills. Right when you think he's standard villain faire, The Reveal shows that not only did he kill his own brother in cold blood, but that he's now masquerading around as said brother and manipulating events behind the scenes to work out in his favor.
Take That, Scrappy!: Gruntilda gets rammed into electrified metal bars by Rouge's foot when her bad rhymes become too much for all of the rest of the Sonic crew.