Power Girl, whose real name is Kara Zor-L, first appeared in All Star Comics #58 (January/February 1976), created by Gerry Conway, Ric Estrada, and Wally Wood. She was introduced as the Earth-Two counterpart to Supergirl, the cousin of that universe's Superman (Kal-L). Originating from Krypton like her cousin, Kara was sent to Earth in a symbioship that preserved her in stasis while providing virtual reality experiences of life on Krypton, causing her to arrive decades after Kal-L as an adult. She joined the Justice Society of America and later Infinity Inc., adopting the civilian identity of Karen Starr, a computer programmer, and becoming known for her distinctive white costume with a window cutout.
The 1985-1986 Crisis on Infinite Earths event merged the multiverse, eliminating Earth-Two and initially retconning Power Girl's origin to make her the granddaughter of the Atlantean sorcerer Arion, with magical powers. This change proved unpopular and was later reversed during Infinite Crisis (2005-2006), restoring her as a survivor from the pre-Crisis Earth-Two and reaffirming her Kryptonian heritage. She continued as a prominent member of the Justice Society of America and Justice League, starring in solo series in 1988, 2009-2011, and from 2023 onward.
In the New 52 era (2011), a separate Earth-2 version of Power Girl (initially Supergirl, Kara Zor-El) existed, but post-Rebirth and events like Doomsday Clock (2017-2019), the original pre-Crisis Power Girl was reintegrated into main continuity on Prime Earth. She has maintained affiliations with teams such as the JSA and Justice League, while exploring personal identity issues, including adopting the alias Paige Stetler in recent stories, solidifying her as a resilient, independent heroine distinct from Supergirl.