A cute little alien girl born with plant DNA coursing through her veins, she is the sole surviver of the Seedrian race who requested aid from the Mobian Hero Sonic in order to defeat the Metalix or whatever their called.
Cosmo is one of two females in the entire series that cute little Tails has fallen in love with, the other being Fiona the Fox (the android version). From their first glance. they develope a strong, unshakable bond, however they refused to admit their feelings, Tails being a little nervous and Cosmo is a little afraid to get with an Animal (thinking that Animals and Plant life aren't qualified for each other).
The finale episode was pretty sad, well at least the Japanese version. Tails was at his most dramatic scene to date, bursting into tears, not wanting to kill Cosmo and admitting his love for the Seedrain. I myself was sad to see those two apart
Cosmo was created by SEGA (Sonic X was created by Sega and it's producer was Yuji Naka himeself), She would actually make a good character in the game series, where Tails can finally get back into action.
The only parts of Sonic X I liked were the Cosmo episodes and the very first episode. You know, the first episode does give a clue as to how Sonic and co winded up on a Human populated world.
Also in Sonic Chronicles, you can see Cosmo's plant in Tails Workshop.
I also thought she would actually be in Sonic Chronicles.
Also to note, she's the only character to wear stockings/hosery
I don't think she'll be in a game because Sonic X isn't canon to the games. Yuji Naka even said himself that they follow seperate storylines entirely. And I think it should stay that way. If they're going to bring Cosmo back, it should be in Sonic X, not in the games. Plus, I think this was just a cameo appearance.
But great pic anyway.