Cosmo the Seedrian

Cosmo (コスモ Kosumo?) is a fictional character and heroine in the Sonic the Hedgehog franchise, debuting as a main character from the third and final season of the anime series Sonic X. She was a female child of a plant-like alien species whose homeworld was destroyed by the villainous Metarex, who, in the years 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, but she sacrificed herself defeat the Metarex for good.

Canon

 * Amy Birnbaum

Fanon

 * Ariel Winter (Justice League: Rings of the Force)
 * Jessica DiCicco (Sonic Mania TV series)

Iago PUC

 * Cosmo appears in Justice League: Rings of the Force, voiced by Ariel Winter.
 * Cosmo appears in the Sonic Mania TV series, voiced by Jessica DiCicco.
 * In Sonic and the Tomb Raider, there is a new character named Mari "Cosmo" Corazon, voiced by Katie Leigh. She is an amalgam of Cosmo the Seedrian and Mari (from the Tomb Raider comics).
 * In the Disney+ crossover miniseries Marvel's All-Star Multiverse, there is a new character named Zooey Blossom, voiced by Tara Strong. Depicted as Miles "Tails" Prower's love interest, the character is an amalgam of Cosmo with Zooey (another love interest of Tails who debuted in Sonic Boom). Zooey is also Sally Acorn's sidekick, a role similar to Tails's for Sonic the Hedgehog.

Moon Silvight

 * TBD

Joint ideas

 * Cosmo is mentioned in DC vs. Sega. In Tails's ending, Tails is shown carrying her seed. And he is still devastated over her death, but is comforted over his grief by Swamp Thing.