Frollo definitely deserves that top spot, but Scar is a close second *nods* Both have no problem with murder. Frollo was all for genocide, killing a baby (who had done nothing but look different), and lusting after a woman to the point that if he couldn't have her - than no one else could either. Not to mention, Disney changed him from his original religious figure status to a political figure to keep away controversy.

Scar was perfectly fine killing his brother (plotting it out in great detail and reveling in it). Though later he insists no one says Mufasa's name later. Could possibly be from guilt, but more likely just wanting everyone only think of him as King. He also was perfectly fine with killing his nephew (both as a kid and as an adult). Then if you follow the Broadway version, he gives off some strong rape-y vibes regarding Nala.

So, the two of them are very similar. Rape-y vibes. Perfectly fine with murder or even genocide, and neither care what happens to everyone else, so long as they get what they want.