Villain, scoundrel, blackguard, knave, rascal, rogue, scamp, rapscallion, miscreant can all denote a low, mean, and reprehensible person utterly lacking in principles.
Villain describes one utterly given to crime, evil, and baseness.
Scoundrel may suggest blended worthlessness, meanness, and unscrupulousness.
Blackguard may imply inveterate depravity; sometimes it is used with a suggestion of angry contempt as the antithesis of gentleman .
Knave may suggest sly trickery and deceit.
Rascal may suggest base dishonesty.
Rogue often suggests the blended roughness and wiliness of a vagabond, but both rascal and rogue are freely used with greatly weakened force and then imply no more than a more or less pleasing mischievousness.
Scamp may describe one given to artful cheating, clever robbery, or interesting escapades and it, too, is often used with weakened force, then suggesting impish and often childish trickery.
Rapscallion may refer to an ill-dressed rogue or rascal rarely successful.
Miscreant typically refers to a singularly conscienceless villain .