Supergirl Season 3 Episode Guide

Supergirl Season 3 is over, but you can relive it all with our Season 3 episode guide!

Supergirl Season 3 Poster

Supergirl Season 3 has come to an end. Here’s our review of that intense season finale.

Scroll through our episode guide below to relive all you of your favorite moments, and the head over to our Supergirl Season 4 news hub to find out what’s in store for Kara Danvers next…

Supergirl Season 3 Episode Guide

Hit the blue titles to go to our full reviews!

Supergirl Season 3, Episode 1: Girl of Steel

Kara (Melissa Benoist) deals with the loss of Mon-El (Chris Wood) by focusing all her energy on being Supergirl and the mysterious new threat against National City.  Alex (Chyler Leigh) confesses a secret to Maggie (guest star Floriana Lima) about their impending nuptials.  A citizen of National City has a mysterious connection to Kara, and Lena (Katie McGrath) makes a bold move.

Original airdate: 10/9/17

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Supergirl Season 3, Episode 2: Triggers

Psi (guest star Yael Grobglas), a thief with psychic powers, attacks National City.  Able to immobilize people by tapping into their worst fears, Psi proves a formidable opponent for Supergirl.  Meanwhile, James (Mehcad Brooks) and Lena (Katie McGrath) are at an impasse, and Samantha starts her new job at L-Corp. 

Original airdate: 10/16/2017

Supergirl Season 3 Episode 3: Far From the Tree

Eliza (guest star Helen Slater) throws Alex (Chyler Leigh) and Maggie (guest star Floriana Lima) a wedding shower, which causes Maggie to reach out to her estranged father (guest star Carlos Bernard).  Supergirl (Melissa Benoist) joins J’onn (David Harewood) on a personal mission.

air date: 10/23/2017

Supergirl Season 3 Episode 4: The Faithful

Kara (Melissa Benoist) investigates a secretive new group whose leader, Thomas Coville (guest star Chad Lowe), has a mysterious connection to Supergirl.  Meanwhile, Samantha (Odette Annable) feels like she’s letting Ruby (guest star Emma Tremblay) down, and J’onn (David Harewood) confesses an old secret.

air date: 10/30/2017

Supergirl Season 3 Episode 5: Damage

When multiple children get sick from lead poisoning, Morgan Edge (guest star Adrian Pasdar) points the finger at Lena (Katie McGrath) and blames her creation of the lead bomb she made to save National City from the Daxamites.  While Lena knows she never intended any harm, she fears there may have been a flaw in her design, leaving her responsible.  Kara (Melissa Benoist) teams up with Samantha (Odette Annable) to clear Lena’s name, but it turns out to be harder than they thought.  Meanwhile, Alex (Chyler Leigh) and Maggie (guest star Floriana Lima) make a crucial decision about the future of their relationship.

air date: 11/6/2017

Supergirl Season 3 Episode 6: Midvale

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 Danvers sisters closer together.

air date: 11/13/2017

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Supergirl Season 3 Episode 7: Wake Up

When Winn (Jeremy Jordan) and the team discover an alien ship has crash landed deep underwater beneath National City, Kara/Supergirl (Melissa Benoist) is called in to investigate.  Meanwhile, Hank (David Harewood) attempts to bond with his father, Myr’nn (guest star Carl Lumbly).  Samantha (Odette Annable), eager for some understanding of the changes she has been experiencing, looks to her estranged mother, Patricia Arias (guest star Betty Buckley), for answers.

air date: 11/20/2017

Supergirl Season 3 Episode 8: Crisis on Earth X

Barry (guest star Grant Gustin) and Iris’s (guest star Candice Patton) wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony.  All of the superheroes band together with help from their super friends like Citizen Cold (guest star Wentworth Miller), The Ray (guest star Russell Tovey), Felicity Smoak (guest star Emily Bett Rickards), Iris West and Alex Danvers (Chyler Leigh) to take on their most formidable villains yet.  Earth’s mightiest heroes – Green Arrow (guest star Stephen Amell), Supergirl (Melissa Benoist), The Flash (guest star Grant Gustin) and White Canary (guest star Caity Lotz) – lead their teams into battle to save the world.

air date: 11/27/2017

Supergirl Season 3 Episode 9: Reign

Supergirl (Melissa Benoist) investigates a mysterious symbol popping up all over National City, tracing its origins back to an ancient prophecy and the mark of the World Killer, Reign (Odetee Annable). Meanwhile, the tension between Lena (Katie McGrath) and Morgan Edge (guest star Adrian Pasdar) continues to build, causing James to step in and offer up some protection, and possibly igniting a spark in the process.

air date: 12/1/17

Supergirl Season 3 Episode 10: Legion of Superheroes

Struggling to heal from her injuries inflicted by Reign (Odette Annable), Supergirl (Melissa Benoist) remains in a dreamlike state, unable to be reached. Mon-El (Chris Wood) recruits one of the Legion members, Brainiac-5 (guest star Jesse Rath), 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.

air date: 1/15/18

Supergirl Season 3 Episode 11: Fort Rozz

As Reign (Odette Annable) continues to terrorize the city, Supergirl (Melissa Benoist) teams up with Saturn Girl (guest star Amy Jackson), and the two recruit Supergirl’s former enemies, Livewire (guest star Brit Morgan) and Psi (guest star Yael Grobglas), 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.

air date: 1/22/18

Supergirl Season 3 Episode 12: For Good

Someone tries to kill Morgan Edge (guest star Adrian Pasdar) and he barely survives. He accuses Lena (Katie McGrath) 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 (Melissa Benoist) steps in to help her friend. Meanwhile, after Sam (Odette Annable) realizes she’s losing time, she confides in Alex (Chyler Leigh) who decides to run some medical tests to see if she can find out what’s going on with her new friend.

air date: 1/29/18

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Supergirl Season 3 Episode 13: Both Sides Now

The DEO captures a second Worldkiller, Purity (guest star Krys Marshall).  Supergirl (Melissa Benoist) and Alex (Chyler Leigh) use very different methods of interrogation with Purity in the hopes of finding out how to defeat Reign (Odette Annable).  However, Purity escapes and attacks the city’s subway tunnels.  Meanwhile, J’onn (David Harewood), Winn (Jeremy Jordan) and Mon-El (Christopher Wood) band together to fix the Legion ship.

air date: 2/5/18

Supergirl Season 3 Episode 14: Schott Through the Heart

When Winn’s father dies, his estranged mother tries to reconnect and explain why she abandoned him; a copycat Toyman attacks and the two must work together to stop him; Mon-El tells Kara something important about the Worldkillers.

air date: 4/16/18

Supergirl Season 3 Episode 15: In Search of Lost Time

When Myr’nn (guest star Carl Lumbly) inadvertently causes psychic disturbances at the DEO, Supergirl (Melissa Benoist) must work with J’onn (David Harewood) to contain the resulting chaos.  Meanwhile, Mon-El (Chris Wood) begins training Kara in fighting techniques he’s learned in the future for battling Worldkillers.

air date: 4/23/18

Supergirl Season 3 Episode 16: Of Two Minds

Supergirl (Melissa Benoist) and Imra (guest star Amy Jackson) have different ideas on how to stop the third Worldkiller, Pestilence. However, when both Alex (Chyler Leigh) and Winn (Jeremy Jordan) are seriously injured by Pestilence, Supergirl and Imra team up to stop the destruction.

air date: 4/30/18

Supergirl Season 3 Episode 17: Trinity

Still reeling after learning about Lena’s (Katie McGrath) secret, Supergirl (Melissa Benoist) asks Guardian (Mehcad Brooks) 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.

air date: 5/7/18

Supergirl Season 3 Episode 18: Shelter From the Storm

When Reign (Odette Annable) starts hunting Ruby (guest star Emma Tremblay), Supergirl (Melissa Benoist) and Alex (Chyler Leigh) work together to keep her safe. Supergirl and J’onn (David Harewood) look to Sam’s mother (guest star Betty Buckley) for advice on how to stop Reign and come away with some shocking news.

air date: 5/14/18

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Supergirl Season 3 Episode 19: The Fanatical

When a disciple of Coville’s escapes from what’s left of his cult, she gives Kara and James a journal that could hold the key to saving Sam; someone threatens to expose James if he doesn’t do what they ask.

air date: 5/21/18

Supergirl Season 3 Episode 20: Dark Side of the Moon

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

air date: 5/28/18

Supergirl Season 3 Episode 21: Not Kansas

Kara (Melissa Benoist) makes a major life decision. Meanwhile, J’onn (David Harewood) finds out that special DEO-caliber guns have hit the streets of National City.

air date: 6/4/18

Supergirl Season 3 Episode 22: Make It Reign

Supergirl (Melissa Benoist) learns the true depth of Serena’s (guest star Anjali Jay) nefarious plans for Earth. Supergirl, Mon-El (Chris Wood) and Alura (guest star Erica Durance) must devise a plan to stop her before Serena gets to Earth.

air date: 6/11/18

Supergirl Season 3 Episode 23: Supergirl Returns

Supergirl (Melissa Benoist) and team take on Serena in an epic battle for Earth.

air date: 6/18/18

Here’s everything else we know about Supergirl season 3…

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Supergirl Season 3 Trailer

Here’s the Supergirl trailer that premiered at Comic Con…

Supergirl Season 3 Cast

A host of new characters will appear in Supergirl season 3. 

And now it’s time to meet your Legion!

Jesse Rath (who was great as Alak Tarr on Defiance, a show I still miss very much) will play Brainiac 5. Here’s Brainiac 5’s official character description, courtesy of TV Line

Half computer, half organic life and boasting a 12-level intellect, Brainiac 5 is a member of the Legion of Super-Heroes who travels to National City from the 31st Century to help Supergirl and the DEO battle Reign

The above image is more encouraging than the first look we got at Brainy in the initial teaser. Hopefully he looks good in action.

He joins Bollywood star Amy Jackson, is the telepathic Legion founder Imra “Saturn Girl” Ardeen on Supergirl Season 3. Saturn Girl will be a recurring character throughout the season. 

Saturn Girl’s costume is the best of the three, paying some subtle tributes to some of her comics designs, and it has the closest thing to a classic Legion look that we’ve seen. Mon-El’s look is…disappointing, although the triangle motif as an homage to Kara is a nice touch. But you’d think he’d want to pay tribute to her by wearing a cape.

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Calista Flockhart returned for the show’s season 3 premiere. 

Showrunners Jessica Queller and Robert Rovner stated that Flockhart will be in Supergirl‘s season 3 premiere as Cat Grant and that the current plan is to continue featuring her character throughout the season and potentially beyond.  Flockhart has officially been a Supergirl cast member for some time, but the show’s change of network and personnel has cast doubt on the extent her future participation in the series. For now, it appears that she will remain a regular. 

Chris Wood aslo returned as Mon-El. We spoke to him about it…

Chris Wood on Mon-El’s Future in Supergirl by denofgeek

Katie McGrath has returned as a series regular. She told us a little about the expectations surrounding Kara and Lena’s friendship moving forward…

Supergirl’s Katie McGrath on Kara/Lena by denofgeek

Unfortunately, Floriana Lima left the show as a series regular.

We also said goodbye to Laura Benanti as Alura this season. The good news, though, is that her replacement continues the Supergirl tradition of bringing in vets from previous versions of Superman to fill great roles. In this case, it’s Erica Durance (Lois Lane on Smallville) who stepped in as Alura.

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“Unfortunately Laura, who Greg and I have worked with for years going back to Eli Stone, was unable to continue in the role due to work commitments in NY,” said executive producer Andrew Kreisberg in a statement (via The Tracking Board). “But we are so blessed that Erica has come aboard to offer her own interpretation of Kara’s mother. We had tremendous success with a former Lois Lane last season with Teri Hatcher. We know Erica will continue the proud tradition of legacy actors joining our shows and creating new and exciting takes on classic DC characters.”

Supergirl Season 3 Villain

We know who that big villain for next year is going to be, though. The season finale teased another Kryptonian would be joining the party, and we speculated that this would be relatively recent Supergirl foe, Reign. It’s true.

Odette Anabelle (Pure Genius) was cast as Reign on Supergirl Season 3, and has been owning this season as a villain.

“Greg (Berlanti) and I have wanted to work with Odette for years,” said executive producer Andrew Kreisberg in a statement about the casting back in the summer. “We are beyond excited to have her join our cast in the scary, powerful and heartbreaking role of Reign.”

Reign was created by Michael Green (current co-showrunner on American Gods on Starz, and who worked on the Logan screenplay), Mike Johnson, and Mahmud Asrar.

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Her story kicked off in Supergirl Vol. 1: The Last Daughter of Krypton, which is available on Amazon.

Supergirl Season 3 Showrunner

The big behind-the-scenes change for Supergirl Season 3? Series co-creator Ali Adler left as showrunner, with Jessica Queller and Robert Rovner stepping up to take her place. Adler stayed on as a consultant for the show.