SPOILER WARNING: The following list contains major spoilers for all three seasons of "Justice League Unlimited."

After the events of the season two finale, "Starcrossed," the "Justice League" animated series was rebranded as "Justice League: Unlimited" and greatly expanded the League's roster beyond the original seven. Consisting of various heroes throughout DC Comics lore, the expanded roster made for some pretty unique opportunities for other characters within the DC Universe. For many, it was a gateway into a world of superheroes that didn't involve Batman or Superman.

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CBR is taking a look at some of its most unforgettable moments that stood above the rest. With a variety of different characters and a somewhat episodic nature to its series, "Justice League: Unlimited" succeeded at providing its large cast plenty of screen time and character development. With that said, here's a trip down memory lane of DC's elite group of heroes.

15 Initiation

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Effectively serving as the pilot episode, "Initiation" introduced the scope of just how much change the League underwent after the apocalyptic events that took place in "Starcrossed." Viewers are first introduced to the Emerald Archer himself, Green Arrow, when he's recruited to join the newly expanded League. Despite declining, he gets thrown into a mission alongside Green Lantern, Supergirl and Captain Atom to take down a massive flaming robot in a poverty-stricken country. This robot is no joke, as it takes out all three of the super-powered heroes on the case. As the only hero without superpowers on the mission, Green Arrow puts his life on the line against the raging robot as he manages to shoot a carbon rod into the machine's weak spot that deactivates it and puts an end to its wanton destruction.

When it's all over, Green Arrow still looks set to decline the League's offer. At least, until he sees a certain blonde woman in black aboard the Watchtower and decides it's worth sticking around. As the proclaimed voice of "the little guy," Green Arrow would become one of the most vocal heroes in the series while providing the League with a more human  perspective.

14 For The Man Who Has Everything

Superman For The Man Who Has Everything

In "For The Man Who Has Everything," Superman is taken hostage by an alien parasitic plant, courtesy of Mongul, that places him in a trance and shows him his deepest desire: a family of his own on Krypton. Upon arriving to wish him a happy birthday, Batman and Wonder Woman are caught up with having to fight Mongul while trying to free Superman. Of course, that's much easier said than done given the former ruler of War World's immense strength.

With strong bouts of action between Wonder Woman and Mongul, the episode delved into the emotional psyche of Superman, who is more vulnerable than viewers have ever seen him before.  It's certainly one that tugs at the heartstrings knowing the kind of life he could have led. Even when he's freed from the illusion, getting ripped away meant consciously having to turn his back on the son he'll now never have and forces him to deal with his lonely reality. Mongul certainly gets more than he bargained for in the end as the plant is turned against him.

13 Wake The Dead

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"Starcrossed" had long-lasting impacts in "JLU," and this episode marked an emotional return for Hawkgirl, who made her debut in this sequel series to take down a former comrade: Solomon Grundy. 

After being unintentionally resurrected by a demonic spell, Grundy is a destructive zombie hellbent on destruction. Upon hearing this, Hawkgirl is forced to make a public appearance to fight her former friend. Thanks to the properties of her mace, she alone is able to gain the upper hand out of everyone who fought him. After driving him into the sewers, she pursues him alone. Recognizing her, Grundy knows what needs to be done, and doesn't attempt to fight back as Hawkgirl raises her mace to deliver the final blow, sending him back to the afterlife once again.

The moment showed the culmination of Hawkgirl's continued emotional journey. Already seen as a traitor by the world she protected, having to kill her friend in order to save him was a punishment just as bad as the public scorn and mistrust she has received. It also stood as a symbolic message of Hawkgirl being able to forgive herself for the events of "Starcrossed," where it was revealed that she was never voted out of the League and was free to return whenever she was ready.

12 Kids Stuff

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In her series debut, Morgaine Le Fay and her son, Mordred, obtain the Amulet of First Magic, a powerful artifact she intends to use to rule the world. However, Mordred, wanting to use it for himself, takes the amulet from her and uses its power to banish all adults (including his mother) to another dimension.

To defeat Mordred, Superman, Batman, Wonder Woman and Green Lantern are forced to team up with Le Fay. To fight in a world only populated by children, the heroes are forced to become kids themselves, albeit with their minds and superpowers intact. They get in touch with their more playful, kid sides as they battle Mordred's creations to break his spell over the Earth, with Green Lantern even going full robot-projection mode. Even though they succeed in destroying the amulet, Mordred is still powerful enough to subdue all four of them. But thanks to some playful prodding from Batman, Mordred turns himself into an adult, breaking his hold on the Earth and his eternal youth all in one fell swoop. As a result, all that's left of the once proud Mordred is a feeble old man destined to live on forever.

11 Fearful Symmetry

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In "Fearful Symmetry," Supergirl suddenly finds herself having odd dreams in which she's committing all sorts of mass destruction and murder. When Martian Manhunter is unable to make sense of these dreams, Green Arrow and The Question decide to help her do a little digging.

It is soon discovered that these dreams are connected to something bigger: a clone of Supergirl is operating as an assassin, which explains the visions of murder that the original is seeing. The two are connected, as the clone (known as Galatea) is able to see into Supergirl's mind and seeks to put an end to her once and for all. In terms of combat, she far outpaces Supergirl; she is physically older, faster and more experienced when it comes to fighting super-powered opponents. It is only thanks to a mysterious explosion from an unknown source that their fight is cut short, with the League unable to locate her body in the wreckage.

More questions arise as her injured body is later seen at S.T.A.R. Labs alongside Professor Emil Hamilton, a once-strong ally of Superman, who is revealed to have created Galatea, though exactly for who remained to be seen at this point.

10 The Once and Future Thing (Parts 1 & 2)

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This time-hopping two-part episode follows Batman, Green Lantern and Wonder Woman as they chase after Chronos into the timestream following his stealing from the Watchtower. First, they stop in the Old West and must team up with Bat Lash, Jonah Hex, El Diablo and Pow Wow Smith. The show even pays homage to the original series opening by giving a Western theme to the Western Justice League lineup, as seen in the image above.

Later, the three Justice Leaguers are pushed forward into a not-too-distant future (the "Batman: Beyond" time period, to be precise). Here, an aged Static Shock, Batman (Terry McGinnis) and Warhawk are all that's left of the Justice League. Bruce Wayne is still alive, albeit much older, and he hasn't lost his edge, playing the bad cop in a game of Good Cop/Bad Cop where the Batman from the present is the good cop.

Time-hopping adventures like these are never without their revelatory moments, the biggest of which includes the revelation that Warhawk is the son of John Stewart and Hawkgirl. The future timeline with "Batman: Beyond" serves as an extension to DC's animated universe and establishes continuity between the two properties and also to the hit "Static Shock" series.

9 Patriot Act

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With the League spread thin on various missions, "Patriot Act" has non-super-powered members Green Arrow, Vigilante, Shining Knight, S.T.R.I.P.E, and Stargirl are tasked with participating in a Metropolis parade honoring police and first-responders. When Eiling crashes the parade looking to challenge Superman, this non-super-powered troop must take down the deranged general themselves with no means of backup. This will prove difficult, however, because he's injected himself with an experimental serum that's transformed him into a brown, Hulk-like figure with super-strength and invulnerability.

This group of under-appreciated heroes puts their tools and skills on display against Eiling, getting up again and again despite the odds stacked against them. Unfortunately, the group falls short in the face of Eiling's invulnerability. As he looks to deliver the final blow, he is stopped by the citizens, who remind him that he has become the very threat he feared. Still sticking to his distrust of meta-humans, Eiling flees the scene. Meanwhile, the heroes who fought against him are recognized and celebrated for their courage. Despite not having superpowers, they more than proved their worth as League members.

8 Grudge Match

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A continuation of "The Cat and the Canary," "Grudge Match" shows Roulette re-opening her Meta-Brawl fighting ring with a different twist in mind: an all-female ticket. This time, she plans on using whatever skilled female fighters she can get her hands on, and the League happens to have quite a few of them.

Taking control of Black Canary, Roulette's ring regains its former glory thanks to one of the League's best combatants. Huntress, having quit the League, finds out Roulette has been using mind control on female League members and decides to infiltrate the operation. She soon finds herself in a double match alongside Canary against Vixen and Hawkgirl. In the midst of their fight, they are able to free them from Roulette's mind control right after the villain called upon her trump card: Wonder Woman.

"Grudge Match" was great episode for featuring the League's female members. It was shocking to see how they compared to Wonder Woman, who easily dispatched her teammates, but it was also refreshing to see such an action-packed display among the female League members, as well as see some more character development out of Huntress and Canary.

7 Clash

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As the Justice League's approval ratings continue to decline in light of escalating fears of aliens and meta-humans, their newest recruit Captain Marvel enters. Meanwhile, Superman is still struggling with the idea of Lex Luthor running for President.

Tensions run further when Superman spots what appears to be a weapon underneath Luthor's housing development project and tries to destroy everything in order to prevent it from going off. Marvel opposes his actions and tries to get him to calm down, sparking a battle between the two powerhouses. Their battle destroys most of Luthor's housing project, with Marvel getting in some good thunderbolt shots by transforming back and forth from Captain Marvel to Billy Batson while next to the Man of Steel. Superman emerges as the victor, only to find that the device was a power generator, freeing Luthor of any guilt.

The destruction is caught on camera for all to see, shaming Superman and tarnishing the League's image. A disheartened Marvel quits the team, while Luthor and Waller meet to confirm that their plan to further shame the Justice League worked to perfection, with the battle giving them beyond what they needed. This battle set the stage for what was to come as the League was placed into its most precarious position since "Starcrossed."

6 Panic in the Sky

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After the hacking of the League's Watchtower cannon, the founding members (with the exception of Batman) decide to turn themselves over to the authorities, leaving their base powerless and leaderless. Cadmus decides to use their absence to invade the Watchtower, using armies of cloned Ultimen (a pastiche of the "Super Friends") lead by a recently recovered Galatea.

There were battles on multiple fronts: a rematch between Supergirl and Galatea, the remainder of the League against the Ultimen and Batman's solo mission against Cadmus. It is through the latter that Luthor's true motives are revealed: he intends to give himself superpowers, creating an Amazo android to do so. But, while his plan goes up in smoke thanks to Amanda Waller's intervention, all is not over, as he suddenly mutates and his voice changes to resemble an old foe: Brainiac.

The reveal of Luthor's plan and his merging with Brainiac was a turn few could have expected or predicted. It demonstrates just how smart of a villain both Luthor and Brainiac are, always playing the long game and manipulating the pieces in his favor, using both Cadmus and the Justice League to further his goals.

5 Divided We Fall

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With the Watchtower safe, the founding League members battle with Luthor, who, as mentioned, had fused with Brainiac and had been under its control without realizing it.

Despite their best efforts, the founding members make little progress, especially as the two begin working together. Luthor-Brainiac takes them all out except for the Flash, who quickly gets caught to be used as Luthor's first victim, signaling the same catastrophic events that created the Justice Lords in the previous series. But in an unexpected move, the speedster breaks free and proceeds to run around the Earth so fast that he tears away Brainiac's armor and defeats them singlehandedly. However, as a result, Flash vanishes and disappears into the Speed Force. Fortunately, the other founding members are able to free him before he permanently gets stuck there.

Saving Flash and their reaction to his loss shows how deep the bonds between these seven members go. The creators did a great job foreshadowing this event back in the original "Justice League" when the Flash's death sparked the creation of the Justice Lords, illustrating his value as a founding member and how he helps hold the group together.

4 The Greatest Story Never Told

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There are many heroes within the Justice League who get their time in the spotlight, but there also are many who were destined to stay out of it. Booster Gold happens to be among the latter.

When Booster Gold is called in on the mission against the powerful sorcerer Mordu,  he is relegated to crowd control instead of actual combat. His opportunity for glory comes in the midst of said battle when an accident at S.T.A.R Labs creates a black hole on a scientist's chest that absorbs everything around it. With every other hero busy, Booster is the only one left to stop it.

There is a moment when, after continued failures to stop the black hole, he admits to one of the S.T.A. R. Lab scientists (who he happens to have a crush on) that he was a failure in the future and came back to the past to become somebody he could be proud of. It's a touching moment for Booster Gold, one that makes the audience feel for the character and his plight while adding layers of depth to the hero who doesn't get many opportunities to do good.

3 The Great Brain Robbery

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Lex Luthor was dangerous enough when he was merged with Brainiac and the League barely managed to take him down. So what happens when Luthor gets a hold of super-speed like the Flash and access to the Watchtower?

Needless to say, not a lot of good, as both he and the Flash accidentally switched bodies while each tried to exploit Grodd's mind for their own gain. Now in the speedster's body, the League is stuck chasing Lex-Flash around the Watchtower, who proves a hard catch, breaking out of Green Lantern's shield, tearing down doors with his enhanced speed and creating tornadoes. It is only thanks to quick thinking (no pun intended) from Mr. Terrific that the League is able to subdue Luthor to prevent him from escaping or destroying the League's home.

The switching of bodies between the two was especially impactful for Luthor in Flash's body, as he demonstrated the kind of destructive capabilities viewers rarely see from the speedster. Unlike the original, who often jokes and holds his speed back, Luthor didn't hesitate to create earthquakes and wind tunnels with his vibration and speed powers in his attempt to escape the Watchtower, and it further illustrated the kind of threats Luthor poses whenever he has power in his grasp.

2 Destroyer

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Throughout the entire third season, Luthor was dead set on resurrecting Brainiac once again. In the end, his method (which involved sacrificing Tala) resulted in bringing back someone else: Darkseid.  The first order of business for the ruler of Apokolips: exacting revenge upon Superman and destroying the Earth.

With the Justice League and the Legion of Doom working together to stop the invasion, Superman and Darkseid have their epic clash in Metropolis. Superman has trouble keeping up with him, as Darkseid proves himself more than capable of matching him blow for blow. It soon gets to a point that Superman, recognizing how hard everyone is fighting, finally cuts loose for the first time in his life, unleashing his full strength on Darkseid and blitzing him at a breakneck pace. Darkseid responds by trapping the Kryptonian in an energy field that puts him under immense pain. Only the intervention of Luthor with the Anti-Life Equation saved Superman from certain death.

Superman's fights never cease to amaze. The fact that this was one of the few instances he unloaded the entirety of his strength without holding back signified the limitless nature of what he truly is. By the same token, it also speaks to how dangerous Darkseid is.

1  Epilogue

Batman And Ace In Justice League Unlimited's Epilogue

Even before "JLU," the DC Animated Universe was already a fan favorite, and "Epilogue" tied well into its continuity as it focused on the character of Batman and the legacy of "Batman: The Animated Series," especially as it pertained to its future in "Batman: Beyond."

As the truth surrounding McGinnis' origins are revealed (he's a partial clone of Bruce Wayne), the episode's most powerful moment revolves in a flashback regarding Ace, a member of the Royal Flush Gang. Her incredible mental powers are causing her to die, an act that may obliterate everyone in the city when she finally blows. Because of this, Waller creates a special weapon to kill her lest her powers bring about such a great disaster. Batman volunteers for the task, but instead of trying to subdue her by force, he sits by her side and calmly asks her to fix things. Instead of lashing out, Ace does as he asks and passes away peacefully, with Batman carrying her body away.

A very different Batman is seen from the one many are used to. Viewers see a more comforting version who seems to relates to Ace's struggles of a lost childhood. It stands as the most emotionally and psychologically driven moment in the series, giving viewers a sense of the weight one carries when they become Batman.

Did you agree with our list? What were some of your favorite moments from "Justice League Unlimited?" Let us know in the comments!