The Krang Sister is one of the two secondary antagonists (alongside Krang Three) of Nickelodeon's 38th non-theatrical feature film Rise of the Teenage Mutant Ninja Turtles: The Movie. She is the sister of the Krang Leader and another member of her kind who seeks to conquer the universe with her family.
Vote which fictional character would naturally fit in-universe with a big-named franchise! No time-travel, no interdimensional crap, no "Pooh's Adventures", they would just exist in-universe.