In anime, in non-Japanese cartoons, in anything at all. Who is the absolutely strongest Magical Girl. This question is completely open ended, only limited by the number of magical girls that have been written about, drawn, animated, or in some way created by people who create these works of fiction. Fan-originated characters based on actual known characters (derivative works) or original characters created individuals don't count. Only characters created by actual animation/movie/TV/book companies count.