Supergirl is Kara Zor-El, Superman's cousin from the planet Krypton and one of the most powerful heroes in the universe. She has been a member of the Justice League, the Legion of Super-Heroes and the Red Lantern Corps. The "Supergirl" moniker is a legacy name also used by other female super-heroes involved with Superman and the Superman Family like Matrix, a shape-shifting creature from a Pocket Universe who would later fuse with a woman named Linda Danvers developing angelic powers. Power Girl is the Earth-Two version.
Supergirl first appeared as a one-time fictional character in Superman #123 by Otto Binder and Dick Sprang. Supergirl (Kara Zor-El) was recreated by Otto Binder and Al Plastino, first appearing in Action Comics #252. (1959)
New 52 Multiverse
See Also: Supergirl Titles