Martha Kent was Superman's adoptive mother.
She and her husband Jonathan had been trying to have a child. However, Martha was sadden to discovered she was barren. While driving down a road in the outskirt of Smallville, she and Jonathan survived a meteor shower and found a Kryptonian spacecraft bearing the infant Kal-El. Martha fell instantly in love with the baby, and insisted that they keep the child and raise him as their own, in contrast to her husband's wariness. She chose to name the baby Clark.
Over the years, Jonathan and Martha's loving, supportive parenting instilled in young Clark a strong sense of morality and the importance of helping those in need—thus providing Superman with an essential heroism to match his vast physical power. Even after Jonathan's death, Clark remains close to Martha, occasionally visiting her to talk about recent events in his life.
During a recent visit, Martha revealed that her infertility was the result of her suffering from stage one Van Braun's Syndrome, a rare genetic disorder that destroyed her body's ability to repair itself; her own condition started in her ovaries. Despite this, Martha has accepted her eventual death, regarding it as part of God's plan for her to ensure that she and Jonathan would be available to raise Clark. She has also recently started a relationship with Alfred Pennyworth, butler/father figure to Bruce Wayne, despite both their 'sons' being somewhat unnerved at the idea of their parental figures being involved.