Originally, Supergirl had a very simple origin: she was Supermans cousin from the planet Krypton. It was iconic, and it made sense. However, when Supergirl died in Crisis On Infinite Earths, DC decided that it was a good idea to remove her from canon completely, establishing Post-Crisis Superman as the only survivor of Krypton. Fine. Whatever. When DC eventually realised their mistake (i.e. erasing one of their most popular female characters from cannon), they tried to fix it by creating a new Supergirl: Supergirl Matrix. During the late '80s DC published a story where Lex Luthor from an alternate reality created a Supergirl from protoplasmic matrix goo in order to fight three evil Kryptonian criminals who had escaped from the phantom zone. Thats right - she was created from protoplasmic man goo. This version of Supergirl is similar to Pre-Crisis Supergirl in physical features and power set; however, this version has the ability to shape shift. Eventually, this Supergirl Matrix made her way to main earth where she took on the role as the first post-crisis Supergirl. Eventually, Infinite Crisis occurred and Pre-Crisis Supergirl was reintroduced into the DCU, and Supergirl Matrix slowly began to fade away.