Catwoman

Selina Kyle's early life was defined by tragedy. When she was just a girl, her brutalized mother Maria committed suicide and her violent father Brian drank himself to death not long after. Separated from her younger sister Magdalena and remanded to the Sprang Hall Juvenile Detention Center, an abusive state home for orphaned or delinquent girls, she opted instead to take her chances on the streets of Gotham City. Amid the crime and corruption of the poverty-stricken East End district, she survived through petty theft. Sharp wits and an amazing natural skill as a gymnast led to her becoming the slickest cat burglar the Gotham City Police Department had ever dealt with.

To protect herself, she studied martial arts. Later ex-heavyweight champ Ted Grant (Wildcat) taught her boxing. For a time, she was the most accomplished thief nobody knew. She was also one of the most generous, spreading her ill-gotten gains among the downtrodden and destitute of the East End. She would have continued to rob with impunity if not for the Batman. Spying the Caped Crusader from her window on one of his first outings, she watched him in action and was suitably inspired to take up her own costume when prowling the Gotham night.