When Arrow first premiered on the CW network in 2012, the "Arrowverse" was born. Barry Allen, the young man who would eventually become The Flash was introduced early in Arrow's second season, and the "multiverse" quickly grew to encompass many series, including Legends of Tomorrow on The CW and Supergirl on CBS. However, for its second season, Supergirl is moving to the CW, which many fans believe is where the show should have aired in the first place.

The purpose of this list is to take a look back at the combined Arrowverse, DC's interconnected multiverse of shows all led by the guiding hands of such producers as Greg Berlanti, Geoff Johns, and Marc Guggenheim, among others. We're not looking specifically at crossover episodes (though plenty of those will appear!), but simply the strongest, most well-produced episodes in DC's excellent and beloved television universe. Here are The 15 Best Episodes Of The Combined Arrowverse (Plus Supergirl).

15. Arrow: Salvation (Season 1, Episode 18)

While Arrow has struggled in recent years to juggle its increasingly large cast and dense plot (though sending some of the scene-stealers over to Legends of Tomorrow has proven beneficial so far), we will always have room for the incomparable Paul Blackthorne as Detective Quentin Lance.

In "Salvation," Detective Lance's estranged wife returns to town with a spark of hope that their younger daughter, Sara, may still be alive. Though initially reluctant to believe again, Quentin can't help but be sucked in to the hope that they may one day have their lost child returned to them. Ultimately, Dinah Lance's evidence is refuted and hope is lost, culminating in a heart-wrenching scene in which Dinah expresses her grief to her ex-husband, revealing that she knew of Sara and Oliver's secret love affair, and blames herself for her daughter's death.

In a show about costumed heroes and over-the-top comic book fight sequences, sometimes the most powerful scenes can be those in which two middle-aged parents lament the loss of their child... Of course, the benefit of being a comic book show is that Sara will ultimately be revealed to have survived and become a superhero on her own... Before getting killed for real, and subsequently revived via the Lazarus Pit... But more on that in a bit.

14. Legends of Tomorrow: Star City 2046 (Season 1, Episode 6)

Rip Hunter and his team of would-be legends travel through time and space to save the day and kick butt, often making detours in unique settings that would make a Time Lord proud. One of the more notable episodes in Legends of Tomorrow's freshman season was "Star City 2046," in which the team finds themselves trapped in a grim version of the Starling Vigilante's city, which has been taken over by the son of Slade Wilson, AKA Deathstroke. Meanwhile, the new Arrow, Connor Hawke, AKA John Diggle, Jr, is fighting the good fight but is ultimately powerless against Slade's army.

"2046's" greatest bit of fanservice is the fate of the original Arrow himself, Oliver Queen; having lost the fight to "save his city," he has retired and gone into hiding. Between his bushy white beard, missing left arm, and face full of wrinkles, Queen is the spitting image of his The Dark Knight Returns counterpart. While the episode takes a hit for its flimsy "change the future and you change the past" jargon, it's well-assembled and fully-realized in its vision, in such a way only possible in an interconnected universe like that of Arrow and its numerous sister shows.

13. Supergirl: Falling (Season 1, Episode 16)

Supergirl on CBS was always a strange beast, torn between its Arrowverse roots and hip young heroine, and her more network-friendly day job as an assistant at CatCo Media. Calista Flockhart's stone-cold executive is one part Perry White and two parts Anna Wintour. As excellent as Calista is as the scene-stealing mogul, there's a distinct dissonance between the adventures of Supergirl and the nearly completely different show which encompasses all of Flockhart's scenes.

However, in the final third of the season's run, the lines between the young and old demographics the show was aiming to reach began to finally bleed together, and Supergirl improved substantially as a result; the first episode in this momentum-building upswing was "Falling," which introduced Kara Zor-El to Red Kryptonite, a substance which turns her, not evil, per se, but "all id," as the saying goes.

After being exposed to the toxic synthetic Kryptonite, all of Supergirl's insecurities rise to the surface, and all of her inhibitions fade away. Naturally, one of her first stops is to the CatCo building, where she casually throws Cat off her balcony to her doom, before catching her in a genuinely frightening display of power. It's definitely the turning point of the series, and the fallout from the events of this episode fuel much of the conflict of the remainder of the season.

12. Arrow: Haunted (Season 4, Episode 5)

Legends of Tomorrow debuted as a mid-season show, which meant that the first half of Season 4 of Arrow and Season 2 of The Flash were primarily devoted to setting up that show's premiere. Part of that story was the revival of Sara Lance via the Lazarus Pit, and an old friend of Oliver's being brought in to help understand and treat her condition...

Constantine ran for one half-season on NBC in 2014-2015 and, while it was never able to find solid footing in its niche, it had a small-but-dedicated following, particularly for actor Matt Ryan, who embodied the long-running comic book anti-hero with the character's uniquely graceless finesse.

In "Haunted," John Constantine is brought into the fold, with Ryan reprising his role from the ill-fated NBC show, and posthumously making the gone-too-soon series an official part of the Arrowverse. An expert on mysticism and the occult, Constantine helps bring Sara back to her senses after her experience with the Lazarus Pit. Constantine's presence feels surprisingly natural in Arrow, and we hope he makes many return appearances in the near future.

11. The Flash: The Flash is Born (Season 1, Episode 6)

One of the most memorable metahumans of The Flash's first season was Barry Allen's childhood bully, Tony Woodward, AKA Girder, who proceeds to beat our hero nearly to death before Team Flash is able to deduce a way to neutralize him.

Barry Allen's Flash, while young and headstrong, is noble in his intentions and humble in victory, like a good hero ought to be. However, after besting Girder with a "Supersonic Punch" and seeing his schoolyard nemesis imprisoned in S.T.A.R. Labs' metahuman-proof prison, we had no objection to Barry taking a righteous victory lap. Confronting the defeated metahuman in his cell, Barry reveals his true identity to the no-longer-intimidating Tony Woodward.

After his fight with Girder, Iris West, Barry's foster-sister and love-interest, finally gives Central City's hero a proper name, The Flash. Having confronted a source of childhood torment, Barry has changed, growing from a young man with unique gifts, to a true adult, on a quest to be the hero his city deserves.

10. Arrow: State v Queen (Season 2, Episode 7)

The trial of Moira Queen ended with her anti-climactic acquittal and subsequent debt to Malcolm Merlyn, as well as her ill-advised bid for Mayor of Starling City, which, despite bringing the great Colin Salmon back into the show (along with X-Files veteran Nicholas Lea), stretched our suspension of disbelief even farther than Green Arrow's impossibly accurate sharpshooting skills.

Despite this, "State v Queen" still more than earns a spot on this list for its appearance by The Count and examination of the classic superhero "no kill rule." After spending Season 1 tallying up a pile of bodies which would make The Punisher proud, ultimately driving away his best friend who accuses him of being a serial killer, Oliver spends much of Season 2 trying to be a better kind of hero, who defeats his enemies without killing them.

When The Count (based on the comics' Count Vertigo) returns to deliver his brand of hammy evil to Starling City, Oliver questions his earlier decision to spare his life, which is later exacerbated by The Count's decision to take Felicity Smoak hostage, the same woman who convinced Oliver to spare his life in the first place. Drama! Ultimately, it comes down to a situation where Oliver must kill The Count in order to save Felicity. After she attempts to apologize to Ollie for forcing him to make the choice to kill, he rationalizes that when it comes to saving his friends' lives, "He had you and he was going to hurt you; there was no choice to make."

9. The Flash: Welcome to Earth-2, Escape From Earth-2 (Season 2, Episodes 13-14)

We weren't sure of the relationship between CBS's Supergirl and the rest of the shows on CW, until The Flash traveled to Earth-2, at which point we learned that anything is possible in the Arrowverse, which is actually a multiverse.

While traveling through space and time to the other dimension, The Flash (and the audience) views glimpses of other worlds. Among them, we see a brief glimpse of John Wesley Shipp from the 1990-1991 The Flash series, as well as a view of Supergirl, as played by Melissa Benoist, flying through the air. The 1990s version of The Flash, as well as CBS's Supergirl now exist in the Arrowverse as part of a vast and limitless multiverse.

Once Barry successfully arrives in Earth-2, he is greeted with a veritable deluge of Easter Eggs and subtle references to the far corners of the DC universe, but there's far more to these episodes than mere fanservice; they provide great opportunities for the cast to play mirror-universe versions of themselves, like an evil Caitlin Snow, a jazz-singing Joe West, and an inept Floyd Lawton, whose nickname, Deadshot, is ironic, rather than threateningly foreboding. We hope to make many return trips to Earth-2, maybe to explore its as-yet unseen version of Starling City. We'd also kill to see John Wesley Shipp, one way or another, don his endearingly cheesy 90s costume and fight crime as The Flash again, and we'd put money down that such an event will occur sooner, rather than later.

8. Legends of Tomorrow: Last Refuge (Season 1, Episode 12)

The time traveling antics of Legends of Tomorrow can sometimes be a bit overblown compared to the relatively more realistic sensibilities of Arrow, but it also allows for some seriously wild plots, like that of "Last Refuge," in which the team must defend themselves from The Pilgrim, the Time Masters' top assassin. Only, it's not enough to fortify their defenses or go into hiding, for The Pilgrim is not targeting the team directly, but rather their younger selves.

After arriving just in time to save younger versions of Mick and Sara (complete with an awesome Paul Blackthorne guest appearance), the team manages to get the upper hand on their would-be executioner by kidnapping their younger selves at the moment of their birth. This leads to the true heart of the episode, in which Jefferson, at the behest of his paternal figure, Martin Stein (Victor Garber, whose rapport with Franz Drameh is one of the main highlights of the series) travels to the date of his own birth and meets his father, whom Jefferson had never actually met before, as he shipped off to war and was killed in action just weeks after Jax's birth. Whether or not Jackson's advice to his father will be enough to save his life and change the fate of his family remains to be seen, but it's an emotionally charged scene in a unique episode of an unprecedented show, and we hope that Season 2 brings us more like this one.

7. The Flash: Tricksters (Season 1, Episode 17)

Some younger fans of The Flash might not know much about the 1990s television version of The Flash, but there are nods to it abound in the modern series. John Wesley Shipp, who plays current Flash Barry Allen's father, played Barry himself in the old show, and other characters "reprising" their old roles include Amanda Pays as Dr. McGee and Vito D'Ambrosio as Mayor Bellows; the actor starred as one Officer Bellows on the old show. But the biggest and most publicized connection to the 1990s version of The Flash was the inclusion of the great Mark Hamill as James Jesse, The Trickster.

"Tricksters" is a rare episode, in that it has a huge amount of story footwork to do to set up the finishing stretch of the season, but is willing to hit the brakes to indulge in a delightfully kooky and scary villain-of-the-week, a Trickster copycat who winds up being the son of the original. Yes, of course there is an "I am your father" moment, and it rocks. Meanwhile, the subplot about the origins of villainous time traveler Reverse Flash, a.k.a. Eobard Thawne, begins with a flashback to a shockingly good CGI slo-mo battle which ends with the death of Barry's mother, and culminates with a stunning (and gross) special effects shot of Thawne murdering the real Harrison Wells and stealing his identity in nightmare-inducing fashion.

Trickster would reappear in the also-excellent Season 2 episode, "Running to Stand Still," noticeably leaner and healthier-looking. The Star Wars Diet should be a book, and we'd trust Hamill to write it.

6. Legends of Tomorrow: Night of the Hawk (Season 1, Episode 8)

When the so-called Legends of Tomorrow took a trip to 1958 suburbia, we weren't expecting more than some cheap Back to the Future jokes, of which we received plenty. But we also got so much more, courtesy of none other than director Joe Dante (Gremlins, Innerspace). Indeed, "Night of the Hawk" is less evocative of its obvious inspiration and plays out more like a cross between Blue Velvet and the classic 1960s soap opera, Dark Shadows.

At first, Dr. Stein and the other more nostalgic members of the team are having a blast in the idyllic embodiment of 1950s Americana, until they are reminded that the old-fashioned image of the American Dream barely existed for non-whites, women, and the queer community, a truth which rings even louder considering the wonderfully progressive diversity of the team. Of course, this being a science fiction show, it's not long before an even seedier (and decidedly more fictional) truth comes to light; Vandal Savage has been using a meteorite (of the same ilk as the one which gave Hawkman and Hawkgirl their Hawk-ness) to perform experiments on the locals, turning them into homicidal abominations.

It's probably the wildest ride of any Arrowverse episode to date, with the audacity to go to extreme stylistic ends, and the skill to pull them off. Similar joy can be seen in the later episode, "The Magnificent Eight," in which the team travels to the Old West and does battle alongside none other than Jonah Hex. Seriously, this show is awesome, and everyone should be watching it.

5. The Flash vs Arrow/The Brave and the Bold (The Flash: Season 1, Episode 8; Arrow: Season 3, Episode 8)

Barry Allen was introduced in Arrow, sans superpowers. The Green Arrow made a brief appearance in the pilot episode of The Flash, but the two heroes didn't truly team up until the two-part, two-show crossover, "The Flash vs Arrow" and "The Brave and the Bold." The long-awaited team-up proved to be everything we could have hoped for. Having a central creative team overseeing both shows, as well as their shared aesthetic made the crossover event feel completely natural, despite the two heroes' varied power sets.

Like in The Avengers, the heroes had to fight each other before they could team up, so Barry was driven mad by Rainbow Raider's Red Kryptonite-esque rage-inducing superpower. In part two, Flash and Arrow team up to defuse bombs and fight Captain Boomerang, while also dealing with some of the drama of Oliver's possible lost love-child. If there's one minor problem with these crossover events, it's that they can be pretty hard to keep track of on Netflix. Newcomers need an expert telling them which episodes to watch and when. The following year, another two-part crossover event introduced Vandal Savage to the Arrowverse. Savage would go on to feature as the dastardly lead villain on Legends of Tomorrow.

4. Supergirl: World's Finest (Season 1, Episode 18)

While the Flash/Arrow crossovers featured their fair share of drama mixed in with action-adventure antics, the much-hyped Supergirl/Flash crossover was nothing but pure, unadulterated, superpowered joy. In the episode of The Flash, "Versus Zoom," Barry travels fast enough to accidentally create a portal to another universe and travels through it, before emerging just a second later. It is within this second in The Flash's universe that the Supergirl episode, "World's Finest" is set.

Despite having mistakenly marooned himself on Supergirl's Earth with no plan on how to return, Barry handles his fate surprisingly well, and hits things off with Supergirl surprisingly quickly, much to the chagrin of Jimmy, err, James Olsen. It's not long before Flash and Supergirl have to take on an evil dynamic duo... But that's not particularly important.

Regardless of any threatening villain team-ups our heroic pair has to deal with, the best part of this episode is the unbridled chemistry between Melissa Benoist's Supergirl and Grant Gustin's The Flash. The look on Kara's face when Barry disappears and reappears with ice cream cones for everyone is one of pure bliss and a heartwarming highlight of an exceptional episode.

Considering the episode aired just days after the oppressively grim and deliberately joyless Batman v Superman: Dawn of Justice, we consider this episode to be, not a "shots fired" moment, but a simple message: "You do it your way at the movies, and we'll do it our way on television."

3. The Flash: The Fury of Firestorm (Season 2, Episode 4)

Robbie Amell, cousin of Arrow star Stephen Amell, played Dr. Martin Stein's other half, Ronnie Raymond, and was scheduled to reprise his role on Legends of Tomorrow. However, after he proved unavailable, the character was killed off in a heroic act of sacrifice, and Dr. Stein was left without the ability to turn into a human flamethrower. More pressingly, he was slowly dying without a partner to share his power.

After searching far and wide for a replacement, Team Flash narrows the field to two candidates: one is a genius professor, and the other is a teenage auto mechanic with a chip on his shoulder. Ultimately, the scientist who Stein had hoped to be his new partner turns out to be incompatible and a violent jerk, and the young mechanic, Jefferson Jackson, through strength of character, proves to be the perfect match for Professor Stein. We mentioned this before, but as much as we love Robbie Amell (he was great on The X-Files and the underrated teen comedy The DUFF), we feel strongly that the Jax/Stein pairing is the perfect version of Firestorm.

This episode has a subplot in which Barry's new romantic interest, Officer Spivot, becomes convinced that there is a giant killer shark stalking the streets of Central City, even knowing how insane the theory appears. Indeed, even by this show's standards, that's pretty out there. However, in the closing minutes of the episode, Barry is attacked from out of nowhere by none other than King Shark. We knew The Flash was a special show, but it was only in this episode that we came to believe that no DC comics villain, no matter how bizarre, would be considered to be truly off the table.

2. Arrow: Blind Spot (Season 2, Episode 11)

We weren't sure if Slade Wilson's iconic Deathstroke costume was ever going to make a full appearance in Arrow, but it did, and with one hell of a bloody fanfare. Despite the suit appearing in all of its intimidating glory, the true star of "Blind Spot" is young Roy Harper, boyfriend to Thea Queen, Oliver's younger sister.

After being injected with the Mirakuru serum and gaining super-strength and nigh-invulnerability, Roy tries to become a vigilante hero like his idol, the Arrow. With the help of local contact Sin (the plucky and under-utilized Bex Taylor-Klaus), Harper takes on a sexual predator, but loses control of himself in his bloodlust and nearly kills the man with his bare hards.

Colton Haynes is great as a would-be vigilante, and this episode marks the true start of he and The Arrow developing their Batman and Robin-styled relationship. As a funny bit of trivia, the last line of the episode is Roy asking the hero, "When do we start?" before the screen triumphantly cuts to black. Captain America: The Winter Soldierreleased later that year, ends exactly the same way, with Anthony Mackie's Falcon delivering the line. Coincidence? Well, probably. Almost definitely, but we're sure it factors in strongly to any number of conspiracy theories about the Marvel vs DC cinematic war.

1. The Flash: The Runaway Dinosaur (Season 2, Episode 21)

A live-action superhero star has never won an Emmy for acting, but there is a very strong point to be made for Grant Gustin in "The Runaway Dinosaur," directed by mega-fanboy-turned big-time Hollywood writer-director Kevin Smith. On one hand, the episode features a return appearance from a now-zombified Girder (from "The Flash is Born") chasing members of Team Flash and ruining Jason Mewes's mother's car, but the main crux of the episode lies within the Speed Force, in which Barry Allen speaks with a God-like watcher of the universe and all reality as we know it.

Barry, in order to regain his speed (lost in battle with Zoom), must earn the privilege, and part of that comes in the form of facing the death of his mother, something he had been running away from his entire life. We're not completely sure of the mysterious intentions of the Speed Force, but it presents to him a reunion with the long-dead Nora Allen, and they read from his favorite children's book, The Runaway Dinosaur, a simple story about how every child with a loving mother is perfectly paired, no matter what. The tears streaming from Gustin's eyes as he recites the story from memory are genuine, as were those in our eyes while we watched that scene. It was surely no coincidence that the episode aired right after Mother's Day, and you can be damn sure we called ours as soon as the credits began to roll.

The previous few episodes of The Flash had gotten a little out of hand with mercilessly putting Barry through the wringer and beating him down at every turn, so it was nice to see him engage in a less physical battle, where the most compelling action sequence wasn't taking down a muscle-bound metallic zombie, but the acceptance of a universal truth, that we all lose people we love. It's not fair, it's not right, and it hurts for a long time, but the only thing we can do to honor and remember them is to move forward and find strength in carrying their memory with us.

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That's all, folks. Do you agree with our choices? What are your favorite episodes within the Arrowverse, and why? Sound off in the comments below!