Cosmo is a character that appears exclusively in the Sonic X anime series. She was a female child of a plant-like alien species whose home world was destroyed by the villainous Metarex, who, in the time that followed, left Cosmo as the sole survivor of her kind. To thwart the Metarex's ambitions for universal dominance, Cosmo joined Sonic the Hedgehog and his allies in their war against the Metarex, eventually becoming a love interest for Miles "Tails" Prower.