How are Supergirl and Superman related?

Supergirl, most commonly known as Kara Zor-El, is the cousin of Superman.12

Their familial connection is rooted in their shared heritage from the planet Krypton. Kara’s father, Zor-El, was the brother of Superman’s biological father, Jor-El. When Krypton was destroyed, Zor-El sent his daughter to Earth in a rocket to join her cousin. While their exact ages and the circumstances of their arrivals have been adjusted across various comic book iterations—often involving suspended animation to explain why she arrives later than her cousin—the core relationship remains that of cousins who are both survivors of their home world.12