Kara Zor-El is Superman's teenage cousin who was sent to Earth at the same time as baby Kal-El to watch over him and help raise him. However, she was cryogenically frozen in space and didn't age. Years later, when Kal-El was now an adult and a superhero using the name Superman, Kara landed on Earth, still a teenager. She gained powers from living under a yellow sun and became her cousin's partner, Supergirl, also adopting the alias of Kara Kent for use in her civilian life.