Robin,
the greenhorn sidekick.
Jason Todd of Earth-1
Born: c.1970
Started career: c.1983
First comic book 1983.
Jason Todd's parents were circus acrobats who'd known Dick Grayson's parents before they were killed. Like Dick, Jason was learning the ropes at an early age. After his parents were murdered by the deformed criminal called Killer Croc, the orphaned boy was taken in by Bruce Wayne.
Bruce revealed that he was secretly the Batman, and Jason was soon trained to become the new Robin, replacing Dick Grayson, who'd gone on to become Nightwing.
Jason was just getting established as Robin at the time of the Crisis on Infinite Earths, which ended the Earth-1 continuity in 1985.
In the hypothetical future of Earth-1, Jason would assist batman in dealing with the riots that would plague Gotham in the late 1980s, and would aid in climatic battles against some of the Batman's most dangerous foes. It may have been in one of these conflicts that Jason would lose his life around 1990. Jason's death would cause Bruce to retire from being Batman for ten years.
[Although pretty much a Dick Grayson clone at the start, writers soon took the opportunity to contrast the new, inexperienced Robin against the veteran Robin that Dick had been. The portrayal of the Jason Todd Robin as a somewhat insecure beginner struggling to get his feet under him wasn't popular with readers, who felt like he was a whining wimp.]