Stephanie Brown/Spoiler
Stephanie Brown is the daughter of the villain Cluemaster. She never intended to be a hero long-term, but when her father got out of prison and resorted to a life of crime she took up the mantle of Spoiler. Her idea was that she would spoil his plans. During one of her escapades to spoil her father’s plans she met Robin (at that time Tim Drake) and developed a crush on him. This would lead to her taking on the vigilante role of Spoiler on a permanent basis. Eventually this would lead to her being trained by not only Robin, but Nightwing and Batman as well.
As the Bat Family began to go through tumultuous times, Stephanie became the first character to take on both the mantle of Robin (though for a short time) and Batgirl. She has now proven herself to Batman and the rest of his allies.