Kara Xoo was a Quarren woman, a female member of the marauding group known as the Nihil. By the time the Battle of Kur occurred, she had achieved the Storm rank within Kassav's Tempest, leading her own unit. After Gwishi and Klinith Da, members of Xoo's unit, were captured in a skirmish on the moon Wevo during the Strikes, she sought vengeance by launching an attack on the planet Dalna. Xoo was the commander of the starship called the Poisoned Barb.
Following the disappearance of Pan Eyta, who was presumed dead after a failed raid on the Cyclor Shipyards, Xoo received a promotion. She took Eyta's position as the third Tempest Runner of the Nihil.
The character of Kara Xoo was created as part of the Star Wars: The High Republic multi-platform project. Her initial appearance was in the 2021 middle grade novel titled The High Republic: A Test of Courage. Justina Ireland authored the novel, and it was published by Disney–Lucasfilm Press. The design of Xoo was conceived by artist Jeffrey Thomas, who chose to give her more nautically-themed clothing to differentiate her clothing from Marchion Ro's. Thomas based the design of Xoo's mask off of the helmet worn by Black Manta, an aquatic-themed supervillain appearing in comics published by DC Comics.