Best exemplified in the episode "Providence", where the scenes with the heroes at their Darkest Hour are interspersed with what the bad guys are up to. Quite a few fans found the baddies more fun to watch.
Ward! It's really saying something that critics and fan alike complimented the show for not trying to redeem him and turn him good.
Gideon Malick, as played by the late, great Powers Boothe, sells the role of HYDRA leader with an enormous amount of gravitas, enough to intimidate even Ward despite being a Non-Action Big Bad.
Hive, as the original creator of HYDRA, is a pretty evil bastard, being a twisted squid-faced parasitic cult leader who brainwashes Inhumans and devours regular humans. He's also easily one of the coolest threats the show ever faced and one of the best villains in the MCU.
Ruby Hale, due to being a solid Evil Counterpart to Daisy and the interesting dissonance of being a complete psychopath who also happens to be a snarky teenager with attitude problems.
Alias: Julian Sark is the epitome of this trope. He's young and attractive, he frequently wears expensive, elegant suits, and his dry sense of humour produces numerous amusing quips. Sark even sports stylish sunglasses to enhance his villainous awesomeness.
In Family Matters, Extraverted Nerd Steve Urkel's formula based off the "cool gene" transformed him into Stefan Urkél, who was suave but amoral. However, this was subverted in Stefan's next appearance, where Steve revealed that he'd accidentally involved the "evil gene" in the formula; from then on, Stefan was both cool and nice.
Averted in most of the show's main antagonists. Most of them are Hate Sink.
Mike, Gus, and Walt from Breaking Bad are undeniably villains, but they're so brilliant and badass that it's hard not to admire them.
For an even clearer example, Walt is far cooler when he adopts his Heisenberg persona than he is when he's being himself.
Leonel and Marco Salamanca, known as "The Cousins". They wear awesome clothes (shiny sharkskin suits and cowboy boots with silver skulls), they're incredibly calm and collected, they walk unflinchingly even into cars, and they are equipped with an silver axe.
Arguably, one of the main points of Gotham, as is frequently the case with the Batman mythos. The Penguin, the Riddler, Jerome Valeska, Carmine Falcone, Hugo Strange, Azrael, and many others are all liked for being Creepy Awesome (and occasionally hilarious) adaptations of the characters from the comics, many of whom (like Mr. Freeze and the Riddler) have never had a good live-action adaptation before. Even the MadHatter is popular.
For some reason, evil, batshit insane, brain-stealing villain Sylar from Heroes is a lot cooler than sane, geeky Sylar. Apparently, evil wears contacts. Ditching the specs (and also acquiring stubble) seems to be mandatory for characters taking a walk on the dark side.
The ruthless Adam Monroe scores much higher on the coolness factor than either Hiro Nakamura or Peter Petrelli, the two heroes that he interacts with.
Spike, who, before he was turned into a vampire, was laughed at and wrote "poncy poetry", whereas when he was sired, he became all bad ass. (His actor, James Marsters, has since made this his specialty, as the rest of this page shows.)
Evil Angel is about seven times cooler than Good Angel. It probably has to do with the lack of brooding. Evil Angel is funny. He also gets several times smarter when he goes evil, which was lampshaded in the episode Awakening.
In an alternate universe, Xander and Willow got rid of their geeky sides after vampirization, instead opting for black leather and a smooth demeanour.
Faith thought this was the case for a while, mostly as a result of her living conditions improving (going from living in a roach motel that could be and was attacked by vampires, to a giant studio apartment that had all the furnishings and luxury items one could want), until she saw what she had become and attempts suicide by Angel, then Buffy.
Consider Wesley from Angel: glasses on — the scholar and gentleman of the group. His attempts to be baddass are laughable. Glasses off — beds Lilah, keeps a woman tied up in his closet, breaks rogue Slayers out of jail, and tortures junkies for information.
The Daleks, especially in the revived series. They might look goofy at a glance, but they are a Higher-Tech Species and a single one them can take own dozens of armed humans with ease, and that's without bringing in their bigger weapons.
Contrast Patrick Troughton as the playful and impish Second Doctor, and as the frilly-shirted, pleather-covered, exotic and sleazyDiabolical Mastermind Salamander in "Enemy of the World". Similarly, contrast Tom Baker as the childish and manic Fourth Doctor, and as the dominating, darkly charismatic and sadomasochistic Evil Twin Meglos. Both of the Doctor roles are Adorkable. Both of the villain roles ooze a staggering of coolness that you would not see in the Doctor performances.
All three of the villain characters played by Peter Miles - Dr Lawrence, Professor Whitaker, and especiallyNyder. And all in different ways - Dr Lawrence is Evil Is Hammy, Nyder is Creepy Monotone, and Whitaker is pretty much exactly between the two.
Brother Lassar. He's played by Anthony Head. Nothing more needs to be said.
Captain John Hart of Torchwood. Kills someone and then says, totally bored, "Thirsty now". Casually admits he killed someone, apologises for the mess, clears a bar of all he considers ugly, and orders one shot of every drink in the bar. Then drinks what appears to be a bottle of Vodka. In one go. With no noticeable side effects. Comes out with regular quips. The only person who really gets the better of him is Gwen Cooper. It helps the same actor played Spike in Buffy, and there is a definite similarity between the two.
The villains in Batman were always more colorful than Batman and Robin. No wonder so many established actors were willing to play them!
Mark Sheppard plays delightfully evil characters in Firefly, Supernatural, Leverage and White Collar, among others, that seem to come out on top and have lots of fun while doing so. From his shiny shoes to his amazingly charismatic voice, he effortlessly manages to outshine and out-cool the regulars on the show.
Generally averted in Criminal Minds, where the various killers usually come across as rather pathetic as soon as they're not in a position of power, (they are usually trying to fulfil some fantasy or make themselves feel better about some perceived deficiency in themselves,) and the whole focus of the show is on The Profiler team proving themselves intellectually superior to the killers by outsmarting and catching them. The only exceptions to this tend to be killers like the Boston Reaper, who gives off this vibe due to his extremely high level of competence and his apparent lack of any fantasy-fulfilment (he just kills because he's an evil sadist who enjoys tormenting his victims and being notorious).
Averted with most of the other villains though. Cora was too relentlessly monstrous, Greg and Tamara were just boring (and clearly pawns), and Peter Pan was just a selfish dick.
Maleficent. Her dragon-fire burned so hot that it reduced an entire forest to nothing but blackened branches - and left a single tree still burning for "half a lifetime", as Rumplestiltskin puts it. She was also powerful enough to put a sleeping curse on all of Storybrooke in mere seconds without breaking a single sweat. The good guys really have their work cut out for them this time.
The good guys are cool and all, but let's be honest, the Monsters are the real stars; creativity in these things is the key that's made the show so popular.
"That was your lesson for today! Your homework: Feel the emotion that rages within you! It is called—FEEEEEAR!"
Any good Super Sentai villain should embody this. Prime example is Shinkenger's Big Bad Dokokou. He's taken on the titular heroes more than once and flattened them. He manages to reduce an apparent Dragon-in-Chief Akomaru to Big Bad Wannabe when he appears.
The Legion of Doom which has the above mentioned Eobard Thawne, Damien Darhk, Malcolm Merlyn and Leonard Snart teamed up together, all in one awesome package.
The Ultra Series kaiju tend to be this, especially Zetton, Alien Baltan, and Red King. Gomora averts this by changing sides in Ultra Galaxy. The standout example is Ultraman Zero's main villain Ultraman Belial, who's been brought back many times as a result of this trope and Joker Immunity.