Superman’s cousin, Kara Zor-El from an alternate Earth. Basically Supergirl all grown up. Apparently years of absorbing yellow sunlight causes her breasts to continually expand, and it became sort of an ongoing joke in the halls of DC.
Drawn in my patented QuickPaint style using Clip Studio Paint Pro on a Surface Pro 4. Here is the time lapse video:
And here is the B&W variant for the collectors: