Supergirl is the 17 year-old cousin of Superman and the last known Daughter of Krypton. Trapped in suspended animation moments after escaping the destruction of the planet Krypton, Kara Zor-El finally managed to reach Earth only to discover her "baby cousin" had grown to become one of the planet's greatest heroes.
Adopting her cousin's symbol, Kara struggles to adapt to life on Earth; torn between the desire to live as a normal teenage girl and the desire to uphold the heroic legacy of her cousin.
When the Kryptonian scientist, Jor-El, attempted to warn the Science Council of the planet's impending destruction, while the council dismissed his assertions as paranoia, Jor-El's brother, Zor-El, heeded his brother's warnings and reverse-engineered force field technology left behind from when Brainiac bottled the city of Kandor. Although Zor-El could not perfect the device, he did succeed in creating a force field bubble that would enable Argo City to survive Krypton's destruction. However, Brainiac sensed that his technology was being used elsewhere and tracked Argo City down. He assimilated the city and merged it with the bottled city of Kandor as Krypton was in the process of exploding.
During the assimilation, Zor-El and his wife, Alura, sent their daughter, Kara Zor-El, in a rocket ship programmed to follow after that of baby Kal-El to Earth. While she was originally intended to look after her infant cousin upon their arrival, her rocket was caught in a meteor that sent her rocket off course and trapped her in stasis for decades.
When the meteor Kara's rocket was trapped within entered Earth's sector on a collision course with Earth, U.S. President Lex Luthor attempted to use the meteor, which was obviously of Kryptonian origin, in a campaign to make Superman a public fugitive. While Luthor issued a considerable bounty for the hero's capture, a bounty that numerous villains attempted to collect, and recruited a small taskforce of heroes, lead by Captain Atom, to apprehend him, the Batman aided the hero in fending of the bounty hunters and well-meaning apprehenders. As the meteor was destroyed by Captain Atom, Luthor attempted to kill Superman himself; publicly donning his LexCore battle armour to engage the hero in Metropolis only to be defeated and publicly outed as having formed an alliance with the New God, Darkseid for weapons and Apokoliptian technology.
While Luthor's presidency was revoked, the villain escaped and the meteor's destruction resulted in fragments of Kryptonite meteors being scattered across the planet. One such fragment contained Kara's rocket, which crashed into the Gotham City harbor. Awakening from stasis, Kara commandeered the Batboat when the Batman arrived to inspect the meteor and discovered the rocket. Exhibiting enhanced powers and strength, in an unfamiliar city unable to speak or understand the language, Kara inadvertently caused a trail of destruction through the city before being subdued by Batman after he deduced she was a kryptonian.
After alerting Superman, the two kryptonians converse and she tells him of their relationship as cousins. Ecstatic over the possibility of no longer being the last of his race, Superman takes Kara into his confidence, teaching her about life on Earth before Wonder Woman abducts her after receiving a prophesy that she would be abducted by Darkseid. Taking Kara to Themyscira, Diana begins training her in combat despite Superman's rejections, however, Kara is still abducted while the Trinity and Amazons are distracted by an army of Doomsday clones.
- Supergirl (Legends PvP)
- Supergirl (Vendor)
- Supergirl (Metropolis General Hospital)
- Supergirl (Fortress of Solitude: Power Core)
- Hallucination (Supergirl)
- Supergirl (Brothers in Arms)
- Enslaved by Brainiac, Supergirl is an opponent in the Fortress of Solitude: Power Core raid.
- Supergirl is a playable character for Legends PvP.
- Superman will contact you to locate Supergirl, who disappeared while investigating the rampaging metahuman patients at Metropolis General Hospital. She is being held captive by Doctor Psycho inside. Doctor Psycho would also conjure hallucinations of her, Power Girl and Wonder Woman in battle.
- Supergirl, located in the Meta Wing of the JLA Watchtower, will initiate the Level 30 mission to locate and assist her cousin, Superman, who is currently inside the Daily Planet building that is being shrunk and bottled by Brainiac.
- Supergirl is among the powerful beings captured and brainwashed by Granny Goodness in Halls of Power Part II. Heroes run the risk of fighting her in the Fatal Exams Alert.
- Supergirl is called upon by the Justice League to investigate reports of metahuman experimentation in a LexCorp-funded wing of Metropolis General Hospital. She finds extensive evidence of metahuman experimentation conducted by Dr. Psycho and attempts to liberate the meta-humans. She is thwarted and her DNA sampled by one of the new metahumans supported by the Secret Society of Super-Villains working for Lex Luthor.
- Supergirl is an iconic opponent for villains in Alternate Metropolis in the Brothers in Arms operation.
- Supergirl appears randomly as an opponent in the Police Station Tier 3 Duo.
- Supergirl first appeared in Action Comics #252 (May 1959).
- Supergirl is voiced by Adrienne Mischler.
- As the two are separate versions of each other from alternate Earths, Power Girl's and Supergirl's hearts beat in perfect sync with each other.
- Supergirl is proficient in hand-to-hand combat from training with the Amazons of Themyscira. As a result she is considered an honorary Amazon of Themyscira.
- While in the comics her skirt is blue, in DC Universe Online Supergirl's skirt is red; possibly taking inspiration from the Supergirl (1984) film.
- Kara is known as the "Trinity Child" due to her being unofficially "adopted" as a protégé by Superman, Batman and Wonder Woman (aka The Trinity).
- Kara owns an orange and white striped tabby cat named Streaky. His name is derived from the fact that he has a lot of household "accidents" that ultimately streaks the furniture.
- Supergirl attends Metropolis University disguised as Linda Lang, the niece of Lana Lang. The duo live together in Hammersmith Tower.