Created by Gerry Conway & Ric Estrada
Power Girl is an anomaly, the sole survivor of the most well-known parallel universe, that of "Earth-2." This parallel Earth perished during the so-called "Crisis on Infinite Earths," which was wrought by a villain from the antimatter universe called the Anti-Monitor.
Her life began on Krypton in Earth-2 universe. In this pre-Crisis universe, Kara Zor-L was the daughter of Allura and Zor-L, and the cousin of that universe's Superman, Kal-L. After Krypton's destruction, Kal-L was her only living relative. Both children had been placed by their parents in space ships bound for Earth.
Kara's ship took much longer than Kal-L's to reach Earth. By the time she arrived, Kal had aged well into adulthood but she had aged only into her teens. Superman and his wife, Lois Lane, welcomed Kara into their family and she very soon joined Kal's friends as a member of the legendary Justice Society of America. (All-Star Comics #58) Power Girl also briefly tagged along as an honorary member of Infinity, Inc.
But for a time, Kara believed otherwise ...
After the Crisis, the newly-single universe began to settle into a new course of history — which included a Superman who was not Kara's cousin. This cosmic unification affected Kara's and other people's memories of their past. She still believed that she was Superman's cousin, but there was no evidence to prove her claim. Instead, Power Girl was told a false history by the ancient Lord of Atlantis, Arion. He appeared to her one day when she had returned to the space ship that brought her to Earth, and claimed that she was his time-lost granddaughter from ancient Atlantis. Her father's name was Calculha; her mother's was unknown, and she also had a brother named Khater.
Arion claimed that her parents had died after Kara was born and that he'd performed experiments on her to engineer her super powers. In the story, he then placed her in suspended animation and sent her into the future to save her from the machinations of his own brother, Garn Danuuth. She aged about 18 years while unconscious, and emerged in the 20th century. (Secret Origins v.2 #11)
All these things were false, but one thing was true — Arion did manipulate Kara at some point. Under circumstances which have yet to be revealed, he implanted Kara with the essence of the evil Scarabus. His aim was to plant the seed for a child which would be the demon's undoing. Apparently Arion only told Kara these lies for the chance to "impregnate" her. She may never know; Arion supposedly perished (JSA #50) but has resurfaced. (Day of Vengeance Special)
Though Arion had given her a history to believe in, Power Girl continued to live with a sense of uncertainty about her past. Feeling disconnected, she threw herself into her adventuring career after the JSA disappeared into Limbo (Last Days of JSA), and joined the newly-formed Justice League Europe, where she remained for a lengthy tenure. (J.L. International v.1 #24-67)
Her powers were significantly reduced in battle with vampires and the Gray Man, after which she lost her vision powers and some of her strength and invulnerability. (JLE #8) During her time with the JLE, an friendly, other-dimensional imp named Ghy assumed the identity of Kara's cousin, Gina Starr and began running her company. Since she was busy with the League, Kara let Ghy continue in this capacity. (JLQ #6) Power Girl also made a strange decision to return once a year to the Underworld and learn from the monstress, Echidna. (JLE #42)
Kara eventually uncovered the crystal which had accompanied her through the ages. (Secret Origins v.2 #11) From it, she unlocked the secrets of her origins, and she ultimately reconnected with Arion, who is still alive and living in New York City. (Arion #6, JLQ #13) Power Girl has no other contemporary relatives, although she had a romantic relationship with Sylvester Pemberton (Skyman) and brief flirtations with Green Lantern II and Aquaman.
Several years ago, Power Girl's body finally began to manifest the son Arion had "created" long ago. a son by means of an apparent immaculate conception. This baby manifested within Kara upon her own proper maturity and was born during the "Zero Hour." (Zero Hour #0) Kara and the child (she was strangely compelled not to name him) were protected from harm by magic, and the baby began to grow at an abnormal rate. They ran afoul of Scarabus, and the JLA and Arion rescued Kara, but the baby vanished shortly thereafter. (Justice League America #93-94) Soon it went off on its own (#97) and reappeared with a mysterious monk; he'd been magically aged to adulthood and bore the name Equinox. (#105-107) Equinox destroyed Scarabus, disappeared, and has not been seen since. (#108)
After her time in the JLA, Power Girl partnered with Oracle, forming the first so-called "Birds of Prey." On her final mission with Oracle, many people lost their lives. This caused her great feelings of guilt and regret; Kara now works with Oracle only very reluctantly. (Birds of Prey #42) She recently rejoined the JSA as a full-time member. (JSA #31)
After years of living with a sense of aloneness, Power Girl eventually rediscovered her true past — and family. After the Crisis that wiped out her home, Earth-2, her cousin Kal and Lois joined Alexander Luthor of Earth-3 and Superboy of Earth-Prime in a new home that existed completely outside of the new reality. From there, Kal and the others could witness events on Earth, but could not leave their "heaven" to intervene.
Over time, however, Superboy-Prime became so powerful that he could breach the crystalline barrier that kept them separated. But with each of Superboy's powerful blows against the barrier, the time stream readjusted and settled into a new reality. One of these blows recreated the history of this universe's previously absent Kara Zor-El. Amid this and other changes, Power Girl's powers began to go haywire, becoming once again more Kryptonian. (JSA #72, 74)
The recreation of a Kryptonian Supergirl in the universe caused an anomaly. When soon the two Karas met with a handshake, Power Girl went mad, her powers out of control. Mr. Terrific hypothesized that their origins were so similar that they were like the same person, and "overloaded" one another. The two quickly made amends. (Supergirl #1)
Karen unwittingly became a pawn Alexander Luthor, who was now hell-bent on creating a "perfect" universe. He sent another Crisis anomaly — the Psycho Pirate — to capture her. (JSA Classified #1) The Pirate's power made her hallucinate a myriad of different pasts, but she also began to subconsciously remember her life on Earth-2. This led her to seek out the Huntress, who on Earth-2 had been her best friend. (#2-3)
Karen eventually managed to escape from the Pirate, but fell into Alexander Luthor's trap. At long last, Kal-L had left their heavenly home and reunited with his cousin. Power Girl was disoriented, but began to remember everything. Luthor claimed that she was not meant to survive the collapse of the multiverse, but somehow fell through a crack, like several others (Dark Angel, Harbinger, Pariah, Lady Quark). The new universe tried to reconcile her existence with false histories. He went on to tell her about the multiverse and introduced her to Lois. When the Karen touched Lois, her memories of Earth-2 came flooding back.
Kal-L cousin believed in Luthor's (false) plan restore Earth-2, and convinced Karen that she was spared for a reason — to help them. (Infinite Crisis #1-2) But after Superman departed, Luthor and Superboy imprisoned Power Girl for use in powering their cosmic reconstruction. (#4) For much of Earth's struggle against Alexander Luthor, Power Girl remained imprisoned there. During this crisis, both Lois (#5) and Kal-L perished. She was able to say goodbye to her cousin before his death (#7), but she was left alone again, save for her friends in the Justice Society.
After this, however, the JSA ceased much of its operations. Karen instead pursued a friendship with her other namesake: Supergirl. Karen accompanied Supergirl on a mission to rediscover her former Kryptonian home. This mission took them to the bottled city of Kandor, where they had to adopt the identities of Nightwing (Power Girl) and Flamebird (Supergirl). (Supergirl #6-9)
A year after the Crisis, the JSA mobilized once again, and Karen was one of several who spearheaded the effort to reorganize. (Justice Society of America #1)
Following the Crisis on Infinite Earths, her JSA membership was in question. Both Power Girl #1 (6.88) and Who's Who Update '87 #4 (11.87) originally declared that the post-Crisis Power Girl was not a member of the Justice Society or Infinity Inc. But many key appearances after that reversed the retcon. She was subsequently shown in flashback in several old JLA/JSA team-ups and it was verified in JSA #31. For no good reason, Chuck Dixon changed her civilian identity to Karen "Steele" in Birds of Prey #42. This should be disregarded, as the JSA series uses "Starr." Her membership in the Sovereign Seven was a fictional story inside the DC Universe.
Among the Psycho Pirate's false histories for Kara was that she was Andromeda from the 30th century Legion, and that she was the Supergirl of the anti-matter universe.
Geoff Johns Says: She represents the success story of the Justice Society. She was one of the first “new kids” to be taken in under their wing and since then she’s grown so popular she can stand next to Supergirl and win. Her taking the role of chairwoman of the Justice Society is just another step in her growth. And she’ll do this with all the guts and energy she’s always had. Her relationship with one of her teammates will become romantic. (from Newsarama)
Power Girl has a very high level of strength and invulnerability. She can also fly, has heat and x-ray vision, and super-senses.
At one time she lost her vision powers and a measure of her strength when near-fatally injured by the Gray Man.
When she was pregnant, Power Girl also manifested certain magical abilities which protected her mystical unborn child, and enhanced her own strength.
In pre-Crisis continuity, one of her friends once commented "If Power Girl were the Supergirl of Earth-1, she’d be fine right now ... But Power Girl comes from a different planet Krypton and unlike [Supergirl], she isn’t indestructible." (All-Star Comics #??)
Comics Presents #56
Power Girl, 4-issue limited series (1988)
JSA #31-87 (2002-2006)
Justice Society of America v.3, current (2007-)