Probably one of the sexiest female superheroes in the DC Universe, Power Girl was created by Gerry Conway, Joe Orlando, Ric Estrada, and Wally Wood, and made her debut in All Star Comics #58 in January/February 1976.

Known as Kara and Karen Starr, she is the daughter of Superman's aunt and uncle and a native of the planet Krypton. The infant Power Girl's parents enabled her to escape the destruction of her home planet by placing her in a rocket ship. Although she left the planet at the same time that Superman did, her ship took much longer to reach Earth.

Power Girl is later stranded on another Earth when a cosmic crisis affects her home of Earth-Two, and later carves out a separate identity for herself from her dimensional counterpart Supergirl once they are forced to coexist.

Power Girl was a member of the superhero team the Justice Society of America through the remainder of the 1970s and 1980s period known as the Bronze Age of Comics. Marvel Comics' then-publisher Stan Lee said in 1978 that when DC Comics created Power Girl after Marvel had introduced Power Man, "I'm pretty annoyed about that. ...I've got to ask the Marvel lawyer – she's supposed to be starting a lawsuit about that and I haven't heard anything. I don't like the idea. ... You know, years ago we brought out Wonder Man, and [DC Comics] sued us because they had Wonder Woman, and ... I said okay, I'll discontinue Wonder Man. And all of a sudden they've got Power Girl. Oh, boy. How unfair."

Having been raised by the Symbioship with artificial Kryptonian life experiences, Power Girl finds it difficult to adapt to life on Earth. However, with the help of reporter Andrew Vinson, she adopts the secret identity of computer programmer Karen Starr (she obtains her knowledge in this field from exposure to Wonder Woman's Purple Ray on Paradise Island). On the pre-Crisis Earth-Two, Power Girl's closest friend is the Huntress, the daughter of the Earth-Two Batman and Catwoman.