Who killed Robin's parents?
Approved answer
Background of the Flying Graysons
As the youngest member of a performing family called the Flying Graysons, Grayson becomes a tragic witness when mafia boss Tony Zucco murders his parents to extort money from the circus that employed them. Following this traumatic event, Bruce Wayne adopts Grayson as his legal ward and mentors him, training him to be his sidekick, Robin.