The adventures of Superman's cousin in her own superhero career.
Alex uses a pair of Obsidian contact lenses to visit a virtual National City where she takes on a whole new persona. Meanwhile, Kelly helps William investigate Lex. Kara deals with difficult news.
Nia's roommate, Yvette, is attacked by a man targeting Dreamer because he doesn't like that Dreamer is transgender and wants her to quit being a superhero. Determined to protect her community from additional harm, Dreamer refuses to give into his threats
Lex tasks Supergirl with protecting Andrea from an anti-tech extremist, but his nefarious purpose goes beyond merely keeping Andrea alive. Meanwhile, Lena moves forward with Non Nocere, with Lex's help.
Mxyzptlk returns with a proposition for Kara – what if she could go back in time and tell Lena her secret before Lex did, would things turn out different? Looking back over key moments throughout the series, Kara must decide if she wants to change histo
Supergirl helps Winn face his greatest fear. After Alex sets out to find evidence against Lex, Brainy must decide between helping his friend or continuing to secretly work for Lex.
As Supergirl tries to thwart a Toyman copycat, Winn Schott returns from the future.
The subsequent complications from the Crisis leave Supergirl to face a chaotic threat.
The Monitor sends Harbinger to gather the worlds' greatest heroes - Supergirl, The Flash, Green Arrow, Batwoman, White Canary, The Atom and Superman - in preparation for the impending Crisis. With their worlds in imminent danger, the superheroes suit up f
Alex is torn between destroying Lena before she can unleash Myriad, or using Malefic to stop the Luthor's mind-control plan. Meanwhile, Khan prepares to wipe humanity from the planet.
Supergirl finally learns the truth about Lena while tangling with Leviathan. J'onn J'onnz makes a discovery about his brother's whereabouts.
While a new villain is under arrest at the DEO, Supergirl uses him to try and understand who is responsible for the recent attacks. Meanwhile, Andrea and Lena think back on their tumultuous past.
On the eve of the worldwide launch of Andrea Rojas's VR contact lenses, Kara and William team up on an investigation that exposes a terrorist plot. Kelly and Alex celebrate an anniversary, but Alex's safety is in jeopardy.
Kara's investigation into William Dey's "criminal" activities results in the shocking revelation he is not who she thinks. Meanwhile, the conflict between Malefic and J'onn J'onzz reaches a boiling point.
Kara attempts to mend her relationship with Lena. J'onn J'onzz takes a deep dive into his memories while Kelly tries to help an old friend.
Supergirl, Alex, and Brainiac thwart an alien attack while William investigates Kara. J'onn J'onzz and Kelly use Obsidian tech to solve a problem.
Kara is surprised to find that CatCo has a new owner who has brought in a star reporter. New couples emerge and explore their budding relationships while J'onn J'onzz receives an unexpected visitor.
Lex Luthor descends upon Washington, DC and summons Lena and Lillian Luthor to the White House. Supergirl realizes she has one last chance to stop Lex and turns to the power of the press to help her.
Kara comes face to face with Red Daughter and the two engage in an epic battle. Determined to find a way to extract the Harun-El, Lena turns to an unlikely source for help - Lillian Luthor. Meanwhile, Alex realizes she's missing parts of her memory, and B
Kara and Lena track Lex to Kaznia, and find Eve but no Lex. Ben abandons his son to go after his wife's killer, which puts him into opposition with Brainiac-5, Dreamer, and the newly superpowered James. Alex and Kelly travel to meet with a woman giving bi
Supergirl tries to convince an Amertek insider to provide her with information proving a connection to Lex. Dreamer agrees to a TV interview, and Brainiac-5 helps James explore the cause of his PTSD.
Kara and Lena head to Stryker's Island to search for clues on how to defeat Lex. At the prison, Kara tries to befriend a nosy prisoner, Steve, who may have insight into what Lex was doing, while Lena studies an array of puzzles Lex left behind in the hope
Supergirl must deal with the destructive aftermath of Lex's nefarious plans. Shocked at what Lex has created, Supergirl faces her biggest challenge yet.
In the wake of Lex Luthor's return, the show flashes back to what he's been doing for the last two years and how his secret machinations and plans have affected Supergirl and Lena.
Secretly furloughed from prison due to failing health, Lex Luthor visits his sister, Lena, to seek her help finding a cure. Savvy as ever, Lena is suspicious of Lex's motives but when she's faced with a life and death situation, she must decide how she tr
Between Ben Lockwood's new push to stir up the anti-alien movement and the Elite's desire to target Lockwood and his minions, Supergirl is concerned about the safety of the American people - both human and alien. When Lockwood organizes a rally, the alien
Manchester assembles a team of Supergirl's old and new opponents to break him out of prison and form The Elite. Meanwhile, President Baker reaches out to Ben and soon asks him for more than photo ops.
With his P.I. shingle newly hung outside his office, J'onn welcomes new clients. Trying to take her mind off what happened at the DEO, Kara decides to team up with J'onn on his latest assignment, which unfortunately ends up tying directly into Alex's curr
Kara travels with Nia to the latter's hometown and discovers that Nia is inheriting the Dreamer power from her mother... which has skipped Nia's sister Maeve. In National City, an outbreak of a new drug rage starts and Alex investigates while asking J'onn
Colonel Haley is upset after Supergirl responds to a distress call from a Navy ship that turned out to be a deadly alien attack. Colonel Haley reclaims the site as DEO territory and demands that Supergirl step aside. After Supergirl refuses to be told wha
Supergirl , The Flash , Green Arrow and Superman engage in the battle of their lives.
Nia has a powerful dream about Agent Liberty but refuses to look at it as a prophetic dream and pushes it aside. After noticing something is bothering Nia, Kara enlists Brainy's help, and the two try to persuade Nia to embrace her destiny. Meanwhile, Manc
James falls in deeper with the Children of Liberty in his efforts to meet Agent Liberty. Meanwhile, Supergirl and Manchester Black follow a lead on Agent Liberty's location, but things take a dark turn. Lena kicks off her first set of trials.
Everyone gathers for Thanksgiving but Kara is feeling down after her televised debate with Ben Lockwood about the anti-alien sentiment coursing through National City. Meanwhile, James and Lena argue about the best way to handle the Children of Liberty.
Colonel Haley makes a surprising decision regarding Supergirl. Kara writes s series of articles highlighting aliens in National City in the hopes that humans will stop being so fearful of them. Unfortunately, the article puts some of the aliens in harm's
To heal Supergirl, Alex assigns Brainiac-5 and Lena to find a way to remove the Kryptonite from Earth's atmosphere. Meanwhile, Mercy and Otis abduct aliens from a DEO facility and use them to attack children and spread fear, and Hank meets an ally in his
Ben Lockwood didn't always hate aliens. Through a series of incidents, and input from his anti-alien father, Ben slowly transforms from a mild-mannered professor into the villainous Agent Liberty of today.
The U.S. people are shaken by the revelation that the President is an alien. As Supergirl tries to quell the unrest, Nia tells James that he should write an editorial supporting aliens. Meanwhile, Mercy launches an attack on L-Corp to shut down the image
Diving back into reporting, Kara welcomes a new cub reporter to CatCo. Meanwhile, James and Lena argue about James' impending indictment for acting as the vigilante Guardian, while Alex and Brainy struggle to get in sync at the DEO. Supergirl is called in
Supergirl must work with J'onn to contain the chaos resulting from Myr'nn's psychic disturbances at the DEO; Mon-El teaches Kara fighting techniques he learned in the future for battling Worldkillers.
Following the death of his father, Winn must work with his estranged mother to stop a copycat Toyman.
The DEO captures another Worldkiller, who escapes and attacks the city's subway tunnels
Morgan Edge accuses Lena of plotting an attempt on his life and Kara steps in to help her.
Supergirl and Saturn Girl recruit Livewire and Psi for a mission to recover a prisoner from Fort Rozz who knows how to defeat Reign.
Supergirl remains in a dreamlike state after sustaining injuries from Reign, so Mon-El recruits Brainiac-5, a member of the Legion of Superheroes, to bring her back.
Supergirl traces the origins of a mysterious symbol to an ancient prophecy and the mark of the World Killer, Reign.
The gang comes together for Barry and Iris's wedding, but the ceremony is crashed by villains from Earth-X.
Kara investigates when an alien ship lands deep underwater beneath National City; Hank attempts to bond with his father; Samantha looks to her estranged mother for answers.
Kara and Alex head home to Midvale for a little R&R. While there, Kara recalls a painful memory of a childhood friend's death and how that traumatic experience brought the Danver sisters closer together.
Morgan Edge blames Lena for children getting sick from lead poisoning.
Kara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl. Meanwhile, Samantha feels like she's letting Ruby down, and J'onn confesses an old secret.
Maggie reaches out to her estranged father when Eliza throws her and Alex a wedding shower, while Supergirl joins J'onn on a personal mission.
A thief with psychic powers attacks National City and proves to be a formidable opponent for Supergirl.
Kara deals with the loss on Mon-El by focusing her energy on being Supergirl and concentrating on a mysterious new threat; Alex confesses a secret to Maggie; a citizen of National City has a mysterious connection to Kara; Lena makes a bold move.
Supergirl challenges Rhea to battle to save National City. Meanwhile, Superman returns and Cat Grant offers Supergirl some sage advice.
Supergirl struggles to decide with whether or not to obey the President's orders regarding Rhea's latest actions. Meanwhile, Cat Grant returns to National City.
National City is attacked by a Phorian, a normally peaceful race with telekinetic abilities.
When Alex is kidnapped, Supergirl and Maggie must work together to save her.
Lena's ex-boyfriend Jack Spheer comes to National City to reveal his breakthrough in nanotechnology that has the potential to eliminate all diseases.
Aliens attack National City with the intention of collecting a large bounty put out on Supergirl.
Supergirl goes on high alert when a new villain comes to National City. In other events, Winn's new girlfriend gets him in trouble with the law and the Music Meister attacks.
Alex and Kara realize they must break the rules to foil Cadmus' latest plot.
When Jeremiah Danvers is rescued from Cadmus, Alex and Kara are thrilled to have him back, but Mon-El is suspicious about his sudden return.
A magical imp called Mr. Mxyzptlk arrives on Earth and wreaks havoc on National City when Kara doesn't reciprocate his feelings.
Lena is arrested when Metallo breaks Lillian out of prison and evidence suggests that Lena is responsible.
A White Martian called Armek comes to National City with the intention of bringing M'gann back to Mars to be punished for her treason.
When Livewire apparently breaks out of prison, Supergirl sets out to recapture her.
While searching for a missing woman, Supergirl and Mon-El end up on another planet where Roulette leads a slave trafficking ring.
As Eliza comes to National City for Thanksgiving, Kara turns to Lena for help when Cadmus unleashes a virus that instantly kills aliens, then is asked by Barry Allen and Cisco Ramon for help with an alien invasion on their Earth.
Supergirl comes face-to-face with Cyborg Superman when she attempts to save Mon-El from Cadmus.
The Guardian arrives to lend a hand when an alien parasite drains Supergirl of her power. Mon-El contemplates his motives when he considers a new career. Alex faces a new reality.
Supergirl faces a ruthless new gang that's been given new alien technology by Cadmus.
Supergirl tries to stop an alien fight club run by Roulette, while Hank gets to know M'Gann.
Supergirl and the DEO are assigned to protect the President when an attack on her causes alien vs. human rights in National City to heat up. Alex investigates the case with Maggie Sawyer while Kara fears Mon-El may be responsible.
Supergirl and Clark team up to stop a new threat emerging in Central City; Alex feels left out while Kara's family stays in town; a pod comes crashing down to earth.
Supergirl is forced to do battle with an unexpected enemy as she risks everything - including her life - to stop Non and Indigo from destroying everyone on Earth.
Non and Indigo use mind control to make the citizens of National City their army, so Kara must find a way to save her friends.
Kara gains a new ally when the Flash arrives from an alternate universe and helps her fight the Silver Banshee and Livewire in exchange for her helping him return home.
J'onn J'onzz reveals how he met Jeremiah Danvers and assumed the identity of Hank Henshaw.
Kara travels to the Fortress of Solitude hoping to find information on how to defeat Indigo, a being from her past who can travel through the Internet. In the meantime, James and Lucy reach a crossroads in their relationship.
Kara battles the Master Jailer while dealing with a second assistant at CatCo and disagreeing with James over the DEO's methods.
A parasitic alien attaches itself to Kara and traps her in a world where Krypton was never destroyed, leaving Alex, Hank and the DEO to fend off a Kryptonian attack without her.
Kara helps Hank face his painful past when a White Martian, who wiped out all of the Green Martians from Mars, kidnaps Senator Miranda Crane who is an anti-alien politician. Adam Foster who...
Kara does her best to support Winn when he hears that his father Winslow Schott Sr. breaks out of prison. His father looks for winn for a reason to become like him. Cat offers Lucy a job ...
A standoff ensues between the DEO and Astra's forces also Non kidnaps Hank, while Kara tries to refute Cat's allegations that she's Supergirl.
Kara and her friends are forced to rely on their inner strength and courage when an earthquake strikes National City, while Alex's mistrust of Hank reaches its breaking point when the ...
Stress makes Kara go too far during a training exercise against a military cyborg commissioned by General Sam Lane, while Cat's mother comes to visit and Winn helps Alex investigate her father's death.
Kara must protect National City from a series of bombings and babysit Cat's son, while James is visited by Lucy Lane.
Kara's foster mother visits for Thanksgiving, while an accident transforms a volatile CatCo employee into Livewire.
Supergirl's powers are put to the test when one of Superman's most formidable enemies, Reactron, shows up in National City to take her down. In the meantime, Cat makes plans to run an expose on Supergirl.
Kara must put doubts aside as she tries to apprehend an escapee from the Kryptonian prison; Cat pressure James for an interview with Supergirl.