Kara Zor-El, also known as Supergirl, is the tritagonist of My Adventures with Superman.

She is the daughter of Zor-El and Superman's paternal cousin. She was sent away by her father moments before Krypton’s destruction, on the very same day as her cousin. But after the Fall of Krypton, Kara was intercepted and then brainwashed by Brainiac to serve as his enforcer in his quest to create a twisted version of Krypton in his image.

Thanks to Brainiac’s brainwashing, Kara was convinced that her mission was to uplift worlds in his new empire. In reality, the machine had been using her to raze any planet he deemed unworthy. Horrified, Kara joined the heroes in stopping Brainiac and became known as Supergirl as a way of honoring Krypton’s hope for peace.