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Supergirl Season 3 Episodes

23 Episodes 2017 - 2018

In the third season of this drama series, Kara (Melissa Benoist) is struggling with the loss of her former lover, Mon-El (Chris Wood), after he is forced to depart Earth. To avoid dealing with these emotions, Kara chooses to focus on her Supergirl alter ego and must face a strange new threat against National City. Meanwhile, J'onn (David Harewood) discovers his father is still alive. Plus, Alex (Chyler Leigh) and Kara unknowingly befriend a Kryptonian survivor.

Episode 1

Girl of Steel

Mon, Oct 9, 2017 60 mins

Kara deals with the loss of Mon-El by focusing all her energy on being Supergirl and on the mysterious new threat against National City, as Season 3 begins. Meanwhile, Alex confesses a secret to Maggie about their impending nuptials; Lena makes a bold move; and a citizen of National City possesses a mysterious connection to Kara.

Where to Watch
Supergirl, Season 3 Episode 1 image

Episode 2


Mon, Oct 16, 2017 60 mins

Psi, a thief with psychic powers, attacks National City and is able to immobilize people by tapping into their worst fears. Meanwhile, James and Lena are at an impasse; and Samantha starts her new job at L-Corp.

Where to Watch
Supergirl, Season 3 Episode 2 image

Episode 3

Far From the Tree

Mon, Oct 23, 2017 60 mins

Eliza throws Alex and Maggie a wedding shower, which causes Maggie to reach out to her estranged father. Meanwhile, Supergirl joins J'onn on a personal mission.

Where to Watch
Supergirl, Season 3 Episode 3 image

Episode 4

The Faithful

Mon, Oct 30, 2017 60 mins

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.

Where to Watch
Supergirl, Season 3 Episode 4 image

Episode 5


Mon, Nov 6, 2017 60 mins

Multiple children get sick from lead poisoning and Morgan Edge blames Lena for creating the lead bomb she made to save National City from the Daxamites. Meanwhile, Alex and Maggie make a crucial decision about the future of their relationship.

Where to Watch
Supergirl, Season 3 Episode 5 image

Episode 6


Mon, Nov 13, 2017 60 mins

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.

Where to Watch
Supergirl, Season 3 Episode 6 image

Episode 7

Wake Up

Mon, Nov 20, 2017 60 mins

When Winn and the team discover an alien ship has crash landed deep underwater beneath National City, Kara/Supergirl is called in to investigate. Meanwhile, Hank attempts to bond with his father, Myr'nn; and Samantha, eager for some understanding of the changes she has been experiencing, looks to her estranged mother, Patricia Arias, for answers.

Where to Watch
Supergirl, Season 3 Episode 7 image

Episode 8

Crisis on Earth-X, Part 1

Mon, Nov 27, 2017 60 mins

Part 1 of 4. Barry and Iris's wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony. All of the superheroes join forces to take on their most formidable villains yet. Earth's mightiest heroes–Green Arrow, Supergirl, The Flash and White Canary–lead their teams into battle to save the world.

Where to Watch
Supergirl, Season 3 Episode 8 image

Episode 9


Mon, Dec 4, 2017 60 mins

A mysterious symbol popping up all over National City is investigated. Its origins are traced back to an ancient prophecy and the mark of the World Killer, Reign. Meanwhile, the tension between Lena and Morgan Edge continues to build, causing James to step in and offer up some protection, and possibly igniting a spark in the process.

Where to Watch
Supergirl, Season 3 Episode 9 image

Episode 10

Legion of Superheroes

Mon, Jan 15, 2018 60 mins

Struggling to heal from her injuries inflicted by Reign, Supergirl remains in a dreamlike state, unable to be reached. Mon-El recruits one of the Legion members, Brainiac-5, to try to bring her back. Meanwhile, Reign continues her rampage on the city so the DEO teams up with the Legion of Superheroes to try to stop her.

Where to Watch
Supergirl, Season 3 Episode 10 image

Episode 11

Fort Rozz

Mon, Jan 22, 2018 60 mins

As Reign continues to terrorize the city, Supergirl teams up with Saturn Girl, and the two recruit Supergirl's former enemies, Livewire and Psi, to form a team for a mission to Fort Rozz to recover a prisoner who has information on how to defeat Reign once and for all. Meanwhile, Alex babysits Ruby.

Where to Watch
Supergirl, Season 3 Episode 11 image

Episode 12

For Good

Mon, Jan 29, 2018 60 mins

Someone tries to kill Morgan Edge and he barely survives. He accuses Lena of being behind the attempt and vows to destroy her. When Lena fears her hatred for Morgan will take her to the Luthor dark side, Kara steps in to help her friend. Meanwhile, after Sam realizes she's losing time, she confides in Alex, who decides to run some medical tests to see if she can find out what's going on with her new friend.

Where to Watch
Supergirl, Season 3 Episode 12 image

Episode 13

Both Sides Now

Mon, Feb 5, 2018 60 mins

The DEO captures a second Worldkiller, Purity. Supergirl and Alex use very different methods of interrogation with Purity in the hopes of finding out how to defeat Reign. However, Purity escapes and attacks the city's subway tunnels. Meanwhile, J'onn, Winn and Mon-El band together to fix the Legion ship.

Where to Watch
Supergirl, Season 3 Episode 13 image

Episode 14

Schott Through the Heart

Mon, Apr 16, 2018 60 mins

When Winn's father dies, his estranged mother reappears, trying to reconnect and to explain why she abandoned him all those years ago. Winn is too embittered from his rough childhood to forgive her, but when a copycat Toyman attacks, the two must work together to stop him. Mon-El tells Kara something important about the Worldkillers, and Alex becomes suspicious of Myr'nn's recent behavior.

Where to Watch
Supergirl, Season 3 Episode 14 image

Episode 15

In Search of Lost Time

Mon, Apr 23, 2018 60 mins

When Myr'nn inadvertently causes psychic disturbances at the DEO, Supergirl must work with J'onn to contain the resulting chaos. Meanwhile, Mon-El begins training Kara in fighting techniques he's learned in the future for battling Worldkillers.

Where to Watch
Supergirl, Season 3 Episode 15 image

Episode 16

Of Two Minds

Mon, Apr 30, 2018 60 mins

Supergirl and Imra have different ideas on how to stop the third Worldkiller, Pestilence. However, when both Alex and Winn are seriously injured by Pestilence, Supergirl and Imra team up to stop the destruction.

Where to Watch
Supergirl, Season 3 Episode 16 image

Episode 17


Mon, May 7, 2018 60 mins

Still reeling after learning about Lena's secret, Supergirl asks Guardian for a favor that could alter his relationship with Lena forever. Meanwhile, with all three Worldkillers united, Supergirl and the team brace for an epic battle.

Where to Watch
Supergirl, Season 3 Episode 17 image

Episode 18

Shelter From the Storm

Mon, May 14, 2018 60 mins

When Reign starts hunting Ruby, Supergirl and Alex work together to keep her safe. Supergirl and J'onn look to Sam's mother for advice on how to stop Reign and come away with some shocking news.

Where to Watch
Supergirl, Season 3 Episode 18 image

Episode 19

The Fanatical

Mon, May 21, 2018 60 mins

Tanya, a disciple of Coville's, escapes from what's left of his cult, and gives Kara and James a journal that could hold the key to saving Sam. Someone learns Guardian's identity and threatens to expose James if he doesn't do what they ask. James contemplates what it means to be a black vigilante without a mask in America.

Where to Watch
Supergirl, Season 3 Episode 19 image

Episode 20

Dark Side of the Moon

Mon, May 28, 2018 60 mins

Supergirl is stunned to discover that a part of Krypton survived. Meanwhile, Alex is attacked while out with Ruby, and Lena considers how far she will go to keep Reign contained.

Where to Watch
Supergirl, Season 3 Episode 20 image

Episode 21

Not Kansas

Mon, Jun 4, 2018 60 mins

Kara makes a major life decision. Meanwhile, J'onn finds out that special DEO-caliber guns have hit the streets of National City.

Where to Watch
Supergirl, Season 3 Episode 21 image

Episode 22

Make It Reign

Mon, Jun 11, 2018 60 mins

Supergirl learns the true depth of Serena's nefarious plans for Earth. Supergirl, Mon-El and Alura must devise a plan to stop her before Serena gets to Earth. J'onn prepares to say goodbye to his father.

Where to Watch
Supergirl, Season 3 Episode 22 image

Episode 23

Battles Lost and Won

Mon, Jun 18, 2018 60 mins

In the Season 3 finale, Supergirl and the team face Serena in a battle for Earth.

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Supergirl, Season 3 Episode 23 image