The origin of the original Robin, Dick Grayson, parallels Batman's story as his parents are murdered before his eyes in a tragic accident. Where Bruce Wayne has Joe Chill to blame for his childhood trauma, Dick Grayson has Tony Zucco.
Tony Zucco first appeared in Detective Comics #38 by Bill Finger, Bob Kane, and Jerry Robinson as part of Robin's origin. However the character has appeared multiple times throughout the Boy Wonder's history, and has spilled over into his career as Nightwing. Additionally, with DC's universe altering events, the history of the character has varied over the years.
The Pre-Crisis origin of Grayson is seen in Detective Comics #38. In this story, Zucco is a mob boss who tries to extort Haly's Circus for money. The owner refuses and in response Zucco sabotages the ropes of the Flying Graysons, causing them to plummet to their deaths before young Dick Grayson's eyes.
Grayson overheard an incriminating conversation between Zucco and his thugs and planned to call the police, but Bruce Wayne stepped in. Batman trained Grayson to be his sidekick Robin and, in his debut, Batman takes Robin to help put a stop to the mobster's latest plan. Robin records Zucco committing murder, putting him away for good and setting Grayson on the heroic path.
After Crisis on Infinite Earths, the history of the DC Universe was altered and the history of Tony Zucco was changed. The story of Zucco's crimes is retold in Batman: Dark Victory by writer Jeph Loeb and artist Tim Sale. In this version of the tale, Anthony "Fats" Zucco is a minor family head under the Falcone crime organization. After attacks from other up-and-coming factions, Zucco decides to expand his operation with plans of making it completely his own, and he sees Haly's Circus as the place to do it.
Zucco kills Grayson's parents to show he means business but goes underground shortly after the killings. He is found by Batman and Dick Grayson (before he would become Robin) where Grayson chased Zucco down. The mobster confessed to numerous crimes concerning the Maronis but suffered a heart attack, seemingly dying in front of Grayson.
In Robin: Year One by Chuck Dixon, Scott Beatty and Javier Pulido it is revealed that Zucco didn't die from the heart attack in Dark Victory, but was instead sentenced to two consecutive life sentences. Seven years after this sentencing, Zucco files for parole. Alfred goes to the parole hearing to plead that the criminal be kept behind bars but doesn't tell Dick anything about the parole, seeing him moving out of the shadow of his past as he has recently become Nightwing.
Dick inevitably finds out about the parole and goes to Blackgate to confront Zucco as he leaves prison. Unfortunately, the mobster is gunned down by the helicopter of a rival crime boss. This was the end of Zucco in the Post-Crisis continuity but a much different fate lay in store for him in the New 52 Nightwing series.
The post "Flashpoint" DC Universe saw many drastic changes and in the Nightwing series by Kyle Higgins and Eddy Barrow one of those changes was the revelation that Tony Zucco was alive and had a new identity. In this continuity, Zucco fled to Chicago and changed his name to Billy Lester. Vowing to turn his life around he married and had a son, but his activities didn't change much. He became friends with the corrupt mayor and helped him with some of his less favorable activities.
Zucco's lies are uncovered when Nightwing finds him, but the former mobster apologizes for his crimes. He even saves Nightwing's life from the villain known as the Prankster. Shortly after, Zucco is arrested by the police. He doesn't resist, accepting his punishment. In prison, he vows to change but his daughter Sonia reminds him that there's one thing he still refuses to face -- the fact that he was responsible for the death of the Grayson family.