|Season 3, Episode 8 (44)|
|A Luthor and a Super||New Krypton|
PART 1 OF 3: CLARK MAKES HIS DECISION- Clark gives Alura his answer. A conversation with Alex forces Lena to confront her feelings for Kara. Brainiac kidnaps an Amazon named Kasia, who had befriended Lesla-Lar during her stint as National City's hero. Lex pays the DEO a visit. Links are discovered between Lex, Coville, and the military.
- Melissa Benoist as Kara Danvers/Supergirl & Kara Schott
- Chyler Leigh as Alex Danvers
- Jeremy Jordan as Winn Schott (Earth-6)
- Katie McGrath as Lena Luthor
- Laura Benanti as Alura Zor-El & Astra In-Ze
- Tyler Hoechlin as Kal-El
- Zachary Quinto as General Dru-Zod
- Odette Annable as Samantha Arias/Reign
- Jenna Dewan as Lucy Lane
- Dianna Agron as Major Raya Zod-El
- Emmy Rossum as Zaora Dru-Zod
- Brenda Strong as Lillian Luthor
- Wallis Day as Nyssa-Vex
- with Claire Holt as Karen Starr
- and David Harewood as J'onn J'onzz/Martian Manhunter
Special Guest Stars
- Chris Wood as M'On-El/Valor
- Leven Rambin as Secretary of State Lyvia Luthor
- and Mehcad Brooks as James Olsen
- Lauren German as President Veronica Banks
- Amy Acker as Brainiac & Vril Dox
- Harry Lennix as Commander Fer-Gor
- Chris Vance as Non
- Tracy Spiridakos as Lesla-Lar
- Chad Lowe as Thomas Coville
- Azie Tesfai as Kelly Olsen
- Paige Turco as Lara Lor-Van
- Casper Crump as Vandal Savage
- Amy Jackson as Imra Ardeen
- Glenn Morshower as General/Secretary of Defense Sam Lane
- Tamzin Merchant as Lyra Strayd
- Andrea Brooks as Eve Teschmacher
- Matt Barr as Tyr-Van
- Skyler Samuels as Rei Kon-Vex
- Alessandra Torresani as Young Jindah Kol Rozz (flashbacks)
- Anjali Jay as Indra Nim Gosa (flashbacks)
- Tasya Teles as Kasia
- Emma Tremblay as Ruby Arias
- Robert Gant as Zor-El
- and Billy Zane as Lex Luthor
- Antagonists: Brainiac, Fer-Gor
- First appearance of Kasia.
- This episode is named after the song by Lindsay Stirling.
- This episode depicts the births of Kara and her sister in flashback.
- This episode takes place on June 6, 2020.
- First appearances of Imra Ardeen and M'On-El.