Reign - SupergirlSupergirl 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.
Crisis on Earth-X, Part 1 - SupergirlBarry and Iris’s wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony.
Damage - SupergirlWhen 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.
The Faithful - SupergirlKara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl.
Triggers - SupergirlPsi, a thief with psychic powers, attacks National City.
Girl of Steel - SupergirlKara deals with the loss of Mon-El by focusing all her energy on being Supergirl and the mysterious new threat against National City.
Star-Crossed - SupergirlA new villain comes to National City, putting Supergirl on high alert.
The Martian Chronicles - SupergirlArmek, a White Martian, descends on National City intent on taking M’gann back to Mars to face her punishment as a traitor.
We Can Be Heroes - SupergirlAfter Livewire seemingly breaks out of prison, Supergirl is intent on recapturing her.
The Adventures of Supergirl - SupergirlWhen a new threat emerges in National City, Kara/Supergirl teams up with her cousin, Clark Kent/Superman, to stop it.
Resist - SupergirlSupergirl grapples with whether or not to obey the President’s (guest star Lynda Carter) orders regarding Rhea’s (guest star Teri Hatcher) latest actions.
City of Lost Children - SupergirlWhen an alien attacks National City, Supergirl and the DEO learn the alien is a Phorian, an otherwise peaceful race with telekinetic powers.