Kara Zor-El is Superman’s teenage cousin from Argo City, which survived Krypton’s destruction intact and protected by a barrier which maintained its atmosphere. When Argo City’s inhabitants began to fall prey to the deadly Kryptonite radiation emanating from their planetoid, Kara’s parents Alura and Zor-El constructed a rocket for their teenage daughter to escape their city’s doom. Kara reunited with her cousin Kal-El on Earth and took on the mantle of Supergirl. In time Kara reunited with her parents after discovering they were still alive, having been trapped by Brainiac with other Kryptonian survivors in the bottled city of Kandor.
Supergirl has appeared in different incarnations since her comic book debut in 1959, as DC Comics revised and reordered their fictional universes multiple times.DC Comics first began to update their fictional universe in 1956 with the introduction of Barry Allen as the new Flash, which began the Silver Age; then in 1986 they reordered their entire universe with Crisis on Infinite Earths, which brought in the Modern Age; and in 2011 they relaunched their entire line again with the creation of the “New 52″ universe. There are also numerous series that stand on their own outside any particular continuity.
Kara Zor-El I (1959-1986)
The adventures of the original Supergirl were published by DC Comics from 1959 to 1985. Supergirl starred in Action Comics, Adventure Comics, Supergirl, Superman Family and Daring New Adventures of Supergirl and made numerous appearances in the Superfamily comics. A theatrical film based on this version of Supergirl was released in 1984 starring Helen Slater. Kara died in the 1985 Crisis on Infinite Earths comic series.
Matrix and Linda Danvers (1988-2003)
Following Kara’s death, DC Comics introduced a new Supergirl named Matrix who was a shapeshifting being created from the genetic matrix of another universe’s Lana Lang. She appeared as a minor character in Superman books for a number of years before gaining her own long-running series in 1996.
In the Supergirl series Matrix merged with a human girl named Linda Danvers. This gave Supergirl a human identity and a new set of family and friends, with references to the Silver Age Kara Zor-El to make her feel familiar to long-time readers. Supergirl/Linda also acquired new powers as an earth-born angel. Linda retired from being Supergirl at the end of her series in 2003, but not before encountering the Silver Age Kara Zor-El in the series’ final six-issue arc.
Kara Zor-El II (2004-2011)
Kara Zor-El was re-introduced into the DC Universe in the 2004 story “The Supergirl From Krypton”. Kara had been sent to Earth by her parents as Krypton was about to be destroyed, with her escape rocket programmed to follow the trajectory of her infant cousin Kal-El. Her ship became trapped in a meteor formed out of the exploding planet and Kara was kept in suspended animation for three decades before her rocket crashed to Earth, where she found that her baby cousin had outgrown her and become the world-famous Superman.
The animated movies Superman/Batman: Apocalypse and Superman Unbound are adapted from two major comic book storylines from this time period.
Kara Zor-El III (2011-)
The animated version of Supergirl from Superman Adventures has also made appearances in the comic books set in the DC Animated Universe.
The digital-first series Ame-Comi Girls features an alternate universe of all-female heroes and villains. The series is action-packed and a lot of fun, but Supergirl is turned into Dark Supergirl shortly after her introduction and spends most of her small screen time incapacitated.
Power Girl is Supergirl’s counterpart from the alternate universe world of Earth 2. She’s a few years older than Supergirl and has a more mature and confident persona. Power Girl replaced Earth 2’s Superman when he retired from the Justice Society of America. In the New 52 universe Power Girl’s backstory has been revised (she is the former Supergirl of Earth 2) and she is teamed with the reimagined Huntress (former Robin of Earth 2) in the series Worlds’ Finest.
Power Girl has her own website at Power-Girl.org