Kara Danvers (War on Leviathan)

Supergirl, or otherwise known as Kara Danvers, is the titular main protagonist of Supergirl: War on Leviathan. She is a superheroine fighting against the evil organization Leviathan.

Read Supergirl: War on Leviathan here

Plot
Note: This is the same Supergirl from the Arrowverse before Season 5 of the show, so she already committed admirable deeds.

Supergirl is first seen fighting off against of rampaging people caused by Leviathan. Then she flies off to a park and meets a strange alien named Rama Khan. The two battled and after he retreated, Brainy informs her of his identity and the natural distasters he causes.

Supergirl then encounters an AI named Hope, possessing a Lexisuit. After the fight, she wonder what was so familar about it.

Rama Khan appears again, claiming that humans do nothing but destroy everything around them. Supergirl then calls him out for his hypocrisy by reminding of his plan to make a volcano explode gushing lava. He claims that he destroys to cleanse the planets. After another battle, Rhan Khan retreats, swearing than Leviathan will one day rule the world. Supergirl tells Brainy about Leviathan's plans.

Supergirl finds an old lady with hundreds of brainwashed people. She is shocked, to which the lady figures how expected that is. The woman reveals itself to be Maggot and Supergirl fought off her army. Afterwards, Maggot is arrested and Supergirl is informed that during the fight, Leviathan using Q-waves to brainwash their victims. She also learns that they send an assassin to cause a tidal wave, so Supergirl heads to Lake Vostok.

There, she finds a person in a suit with mechanical arms named Rip Roar. Supergirl claims that he killed Russel Rogers, however, he says that Leviathan had made him powerful and tried to eliminate her.

After the fight, Rip Roar says that he did what he came for and gets imprisioned. Brainy informs Supergirl that Levithan broke into a government facility to steal Lex's journals and with his research on Q-waves, they can now stabilize their brainwashed victims.

When facing a Martian, he reveals himself as Malefic J'onzz, brother of J'onn J'onzz, and claims he a rough life due to his family and fellow Martian and desires vengeance. After he is defeated, Alex confirms his backstory and send him back to Mars to find peace.

While fighting yet another assassin, she reveals her desperate need to save her father, saying that the only way Leviathan will return him is to do what they say. Supergirl offers to help, but fails and the two fight. After fighting, Alex told her that Leviathan had tried to take something, but failed and now looking for their leader. She also warned her that Hope was back in a new body.

After defeating the AI, Hope's creator was revealed to be Lena Luthor, who found out that Kara had lied to her about her identity. Lena claims that Kara has betrayed her like everyone else, but Kara insisted she only wanted to protect her. She reveals that she helped Leviathan in their plans by giving them the Q-waves they required. Kara wonders why didn't she sent all of her victims after her. Lena claims that for her revenge, she will destroy the world along everyone on it, including everything and everyone Supergirl cares about.

Supergirl tries to track her with the D.E.O.'s computer network but it was taken over by a mysterious virus. She realizes that Leviathan did not try to steal from them, but instead left the virus. The only way to recover it is to head to Mount Norquay.

On the way there, Supergirl encounters Rama Khan alongside with two members Tezumak and Sela. She takes them down and Brainy informs him that Lena is trying to take control of the system, while the leader, Gamemnae, is planning to use the Worldwide Unity Festival to plunge the world into despair.

On that day, Gamemnae tells Supergirl that Lena would give her Myriad (which would allow her to kill every human across the entire planet) if she kills her. She tells her that she would just get rid of her if she does so. The two fought and Supergirl kills Gamemnae with the Anti-Life Equation, defeating Leviathan for good. Calling Alex, she finds her taken hostage by Lena who reveals her plan to use her to steal all of the D.E.O.'s resources and then kill her.

Finding Lena at Mount Norquay, Supergirl demands that she let Alex go. Lena replies that they both betrayed her, and now she is going to ruin her life as revenge. She tells her that she going to blow up a prison with her and hundreds of other people inside. After defeating Lena, Supergirl gets a call from Alex, telling her that she is safe, having been rescued by J'onn during the battle. She tells Supergirl that Lex had uploaded Hope's consciousness into the system. Lena planned to have Lex take control of all of the D.E.O.'s weapons, and to make it seem like they had betrayed the world.

Supergirl finds Lex, who reveals that he told Lena about her identity before she killed him after their pervious showdown. After battle, he claims that it is too late as Hope's consciousness is fully uploaded to the D.E.O.'s network. Supergirl claims she expected that, much to Lex's surprise. She and her friends proceed to destroy the network, destroying Hope as well. After Lex's arrest, they celebrate their victory over a nice dinner.