But with more than 200 total episodes in the rear view mirror, there are really only a handful of villains who have come back time and time again, and who have remained consistently badass.
Here's our rundown of the baddest baddies of the Arrowverse...!
10. VANDAL SAVAGE
While DC's Legends of Tomorrow eventually wore out Vandal Savage's welcome by playing his story out throughout the whole first season, it's hard to argue that he wasn't a really badass threat when we first encountered him.
Savage had a personal connection to the Hawks and to Hunter, and a formidable foe both physically (those hand-to-hand combat skills were pretty wicked) and mystically.
The fact that he's so low down on the list is basically for two reasons: one, his ratio of really great stories to just okay stories isn't very high; and two, he never really evolved.
We meet him at the height of his powers, which means the Legends have to take him down...but it's basically always the same fight.
Sure, he's got a cool look and he's super menacing -- but honestly the best part of this speedster is the fact that he's holding Iris's death over Barry's head...and that's not really enough to make him rate among the best of the best CW villains.
Part of the problem is that while Savitar has an interesting master plan and some cool ways of going about it, he's yet another speedster, and he feels too much like Zoom. Coming back to back, the notion of somebody who's so overwhelmingly, massively too fast for Barry and who wears a dark, twisted version of Barry's costume feels a little on the nose.
Certainily he could move up (or down) based on how well The Flash sticks the landing on the Savitar story this season, but so far, he's the lowest of the Flash big bads, in part because we're feeling diminishing returns on the "ultra mega speedster of the year" bit.
While Zoom certainly felt like a little bit of the same after season one's Reverse-Flash, they managed to keep the speedster thing fresh by having his powers work in slightly different ways, and giving him a radically different agenda than his predecessor.
Why's he not a little higher on the list, then? It's a combination of some really stiff competition up ahead and the fact that so much of his impact relied on what was ultimatley a pretty predictable twist felt a lot more tacked-on than the fun and impressive journey that brought is to Wells/Thawne being the season 1 villain.
7. LILLIAN LUTHOR/PROJECT CADMUS
Supergirl is a show driven by character, by love, and hope, and family. Its villains are not the center of the hero's universe in the way they are for, say, Arrow and The Flash (or the first season of Legends of Tomorrow for that matter), and so ultimately they feel very different from the other shows in the DCU.
The downside to that is that often, the villains don't get a ton of time to shine, and sometimes their motivations feel thin. Not so with Lillian Luthor -- even if they cheat a little by basically making her philosophies so much like her son's that you end up with some chicken-and-egg questions.
The Cadmus subplot would have ranked higher if not for the fact that this point it kind of feels like it's being stretched out. It could rise on the list depending on how Supergirl resolves this plot point in the end of the season...or disappear completely if Queen Rhea turns out to be a better baddie.
We loved the "Invasion!" crossover, and while the Dominators weren't exactly grand Shakespearean villains, they were cool-looking, served their purpose, and antagonized the heroes through one of the most memorable stories the DC Universe has seen yet.
The Dominators' weird dream machines also gave birth to Arrow's hundredth episode spectacular, one of the best single episodes of the series and one of the best CW episodes this season, so while there are some Arrow fans who would rather see a more grounded show without alien invaders, it feels like the writers did "alien invaders" the best way possible within the confines of the series.
Those themes of love, family, and hope? They came into play in a big way for the first chunk of Supergirl's first season, when the first of two big bads was revealed to be none other than Supergirl's aunt, and her mother's spitting image.
Ultimately, Astra's death spurred on a huge amount of story for both Kara and her husband Non -- but she remained a more interesting and tragic figure than Non could ever have been.
4. RA'S AL GHUL
There's certainly an argument to be made that Matt Nable's interpretation of this classic DC villain went out with a whimper rather than a bang, but that ignores the fact that he was an enormously effective adversary for Oliver and arguably the best part of a shaky third season for Arrow.
After a season 2 that left everyone begging for Ra's al Ghul to arrive, the villain showed up in season 3 and seemingly killed Oliver, stabbing him and tossing him off a cliff in a midseason finale that blew everyone's minds and left audiences wondering how they could top it.
Arguably, they never did top it again, and Ra's's departure from the series was a bit disappointing...but so much of what they did with him prior to that final battle in Star City was impressive enough to earn him a spot pretty high up on our list.
3. MALCOLM MERLYN
Merlyn is the Magnificent Bastard villain of the Arrowverse, using his wealthy and influence to avoid the consequences of his season 1 actions, and then blackmailing or manipulating people to just constantly stay one step ahead of consequences for most of the rest of the run.
The revelation that he was the father to Oliver's half-sister was a gut-punch for Oliver and the audience, and the arc that he took his daughter on helped to humanize a character who, after season 3, many fans argued should already have been dead.
Then you bring him into DC's Legends of Tomorrow, where as part of the Legion of Doom he had plenty of opporutnities to show off the skills that made him a fan-favorite to begin with.
Merlyn is the arch-nemesis and Ra's al Ghul is the mastermind, but there's something tragic about the shattered relationship between Slade Wilson and Oliver Queen that just makes Deathstroke a next-level antagonist.
Couple that with a season 2 "final battle" that significantly upped the stakes from season 1 and set the tone for season 2, the fact that he first earned the trust of Moira Queen and then took her life, and the fact that his downfall in both the flashbacks and the modern day represents probably the best use of the parallel storytelling the Arrow writers so often attempt, and you've got a formula for a villain who just sticks with you.
Plus, let's be honest, he's got far and away the coolest costume.
1. EOBARD THAWNE
First of all, there's something positively tragic about a villain whose two major stories have been about trying to get home, and trying to stay alive. If he hadn't been killing people and maiming major characters during the whole affair, those are totally sympathetic goals and he could have passed himself off as a hero.
But Thawne has managed to become the focal point of two of the Arrowverse's best seasons of television: The Flash season 1 and DC's Legends of Tomorrow season 2.
While The Flash was spectacular becuase of the personal relationship he had with Barry and Harrison Wells twist at the halfway mark or so, Legends relied primarily on cool uses of his speed, his intellect, and his cruelty to make him a terrifying character.
And that finale fight (pictured above) was not only an ingenious (and somewhat hilarious) use of his powers, but a reminder that there's still plenty of unexplored awesome even after his apparent death.