It looks like the best villain for Supergirl is also the one that makes her tragic origin far worse. The intergalactic terror known as Brainiac didn't only destroy Kara Zor-El's home, he haunted her dreams well into adulthood.
Cousin to the Man of Steel, Supergirl also came from the planet Krypton and was a resident of the metropolitan Argo City. Like Clark, Kara's father Zor-El was also a scientist and often worked together with his brother Jor-El. Unfortunately, Krypton's days were numbered and the brothers both prepared ways for their children to live on after the calamity. Supergirl and her cousin, Superman, were both rocketed to Earth, but because of some difficulties on her journey, Kara wound up in suspended animation and later arrived on Earth after Clark had already become a full grown man.
Related: Supergirl's Secret Marriage Made Her Death Even More Tragic
But Clark and Kara would both wind up getting a blast from their shared past in Action Comics #867 by Geoff Johns and Gary Frank. Superman has just been in an altercation with Brainiac and is investigating his body along with Supergirl at the Fortress of Solitude. Kara reveals to her cousin that the body is actually just a probe and the Brainiac Supergirl and Superman have fought has never actually been seen before. Kara becomes noticeably shaken describing the horrible acts of Brainiac and the day he stole the city of Kandor from Krypton. Supergirl even lost her best friend among the victims of the villain's invasion. She tells Superman that Brainiac was practically a boogeyman for Krypton's remaining days. Supergirl is so perturbed by the menace she likens him to Lex Luthor, saying that Brainiac is bad for aliens in the same way that Luthor gives humanity
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