Overgirl

Overgirl is the codename to Kara Zor-El from the Nazi-conquered alternate verison of the Arrowverse's Earth-1 known as Earth-X. Much like her heroic counterpart from Earth-38, she's portrayed by Melissa Benoist.

Biography
Kara's pod crash-landed on Earth from the planet Krypton but instead of Midvile, like her counterpart, she lands on a territory ruled by the Third Reich. She would be raised in this world and grow to embrace hate and evil. She would adopt the name Overgirl.

Along with her husband, Oliver Queen (aka Dark Arrow an evil counterpart to Earth-1's Green Arrow ) and Dark Flash, they would rule modern day Earth-X with an iron fist. However, Overgirl would take in too much ultra-violet rays in her, thus, she's dying. She needs a heart transplant from Earth-38's Supergirl.

During Barry Allen and Iris West's wedding, The Third Reich from Earth-X would invade Earth-1. After a few battles, they capture Supergirl, her sister, Alex Danvers, and many of Earth-1's heroes and bring them to a concentration camp on Earth-X.