Ito, the God of Trust and Betrayal from A Moment of Peace, steals dreams and crushes hopes for a living, and has prosthetic hands forged from moments of despair by crows that grew hands to strangle people.
Richard from Looking for Group is an over-the-top chaotic evil necromancer working with an ostensibly good group, and he's easily the most interesting and coolest character in the series.
Black Mage from 8-Bit Theater subverts this trope. Every single other character in the series utterly confirms it.
Xykon's second rule of thumb is "Whatever you want to do, look cool doing it". His first one is "Also, don't bother with pesky morals, they just make you lose". Some of his worst moments are also listed as the best of the comic.
Also, Evil!Vaarsuvius, for the short time we seem them, pulls off some pretty awesome and ridiculously immoral actions. Like a FAMILICIDE !
General Tarquin earned himself fandom adoration for his affability and for being very Genre Savvy. He actually comments that "Audiences always think the villain is cooler than the hero is, anyway.". He starts loosing his cool after the death of Malack, however, making increasingly bad decisions that make him look more and more like a deranged psychopath and less like an Affably Evil villain.
Belkar, the Sexy Shoeless God of War, who defines Heroic Comedic Sociopath and is beloved by the fans.
Bob from Bob and George easily fits here, not only taking on all the other characters in the series (often at the same time), but trying to eliminate the author of the comic so he can take over.
xkcd : Black Hat is one of the only defined characters, and provides most of the Crosses the Line Twice humor.
Oasis from Sluggy Freelance. It helps that she's also hot, and in her first appearance, she was naked.
Rhea in To Prevent World Peace is a fashion designer who specializes in corrupting magical girls through "villain fashions" (which are designed to look cooler).
Mr. Hyde in The Glass Scientists certainly thinks so, and often tries to invoke this trope on purpose, though whether or not he actually succeeds is another matter.
for a living, and has prosthetic hands forged from moments of despair by crows that grew hands to strangle people.