Mary Grayson

Mary Grayson was the wife of John Grayson and the mother of Dick Grayson. She was a trapeze artist from the famous Flying Graysons at Haly Circus. She was killed by a mobster named Tony Zucco who sabotaged her their circus act, which also resulted in the death of her husband, but her son survived, and he is taken in by Bruce Wayne, alias Batman, who trains the young boy to be a superhero who calls himself Robin.

Reference
Super Friends (Season 1)
 * The Planet-Splitter