This article is about the second Robin. For his precursor and successor, see Nightwing and Robin.
Jason Todd was the second hero to go by the moniker of "Robin". After his untimely death, Tim Drake became his successor.
At some point, Jason took the mantle of "Robin" and joined the Team. After Jason died, under unknown circumstances, Tim Drake became his successor.
Background in other media
In the comics Jason Todd was the second Robin. Originally a circus artist whose parents were killed by Killer Croc, after the Crisis on Infinte Earths, this was changed to be less like Dick Grayson's origin. Now, he was a street orphan who tried to steal the tires off the Batmobile.
Jason was killed by the Joker in the highly publicized A Death in the Family event. He was revived when Superboy-Prime changed the multiverse in Infinite Crisis, and has taken the persona Red Hood since then. He continues to fight criminals, but in a more brutal manner, not shying away from torture and murder.
This is Jason's fourth animated appearance. He first appeared in Batman: Under the Red Hood, and his image had a cameo in Teen Titans, the New Teen Titans shorts, and Bat-Mite showed his death scene in Batman: The Brave and the Bold.