Martha Kent

Martha Clark Kent was a farmer in the small town of Smallville, Kansas. She and her husband, Jonathan, became the adoptive parents of the Kryptonian orphan Kal-El after finding the infant alien in a small rocket sent to Earth. The Kents raised Kal-El as their own son under the name "Clark Kent". Martha and Jonathan Kent died as the result of a car accident on the night of Clark's senior prom.

DOOMSDAY CLOCK

Her death was revealed to have been caused by the actions of Doctor Manhattan, who in the past caused Alan Scott to be killed and thus prevented the Justice Society of America from existing. Clark thus never became a superhero as a kid. Inspired by Superman's words to be a hero however, Manhattan undid his alterations. This caused Alan Scott to survive and the JSA to exist, in-turn inspiring Clark to take up the mantle of Superboy as a kid and save his parents from being killed.

It was later revealed that Batman had hidden them on a farm off the grid with the same technology he used to cloak the Batcave, before Clark revealed himself to the world to be Superman.