Supergirl is the superhero name of Kara Zor-EI, cousin to Superman.
Kara Zor-El was the last survivor of Argo City of the planet Krypton, which had survived the explosion of the planet and had drifted through space. When the inhabitants of the colony are slain by green kryptonite which was released by metorites striking the lead barrier, Kara is sent to Earth by her father Zor-El to be raised by her cousin Kal-El, known as Superman. Fearing that she might not be recognized by Superman, Kara's parents provide a costume based on the Man of Steel's own.
On Earth, Kara acquires super-human powers identical to Superman's and adopts the secret identity of Linda Lee, an orphan at Midvale Orphanage. She conceals her blonde hair beneath a brunette wig and functions as Supergirl only in secret, at Superman's request, until she can gain, in his opinion, sufficient control of her powers. After being adopted by Fred and Edna Danvers, Superman decides his cousin is ready to begin operating openly as Supergirl.
In her secret identity, Linda attends Midvale High School as Linda Lee Danvers. In later years, after graduating from Stanhope College, she changes careers several times, holding jobs in student counseling, news reporting, and acting in a TV soap opera titled Secret Hearts. She also attends college in Chicago. Kara has many boyfriends, including Richard (Dick) Malverne, Jerro the merboy from Atlantis, and member of the Legion of Super-Heroes, Brainiac 5. She does, however, shun serious commitments, putting her super-career first.
Supergirl's secret identity is a closely held secret and is known only to Superman, her foster parents, and the Legion of Super-Heroes, of which she serves as a member for a time. Like all Kryptonians, especially in an Earthlike environment, Supergirl is vulnerable to kryptonite. Streaky, Linda Danvers's orange cat, acquires temporary super-powers as a result of its exposure to "X-Kryptonite," a form of kryptonite Supergirl had accidentally created in attempting (unsuccessfully!) to neutralize the effects of green kryptonite. Comet the Superhorse, a former centaur, is Supergirl's equine companion.
Superman: The Animated Series
Justice League Umlimited
Smallville Legends: Kara and the Chronicles of Krypton
Justice League Heroes (PSP version)
Justice League: The New Frontier
DC Universe Online
Super Best Friends Forever