Source: brickipedia.wikia.com

12. Dick Grayson

Let's take this opportunity to talk about the history of Robin’s identity and some of the people who've inhabited it.

First we have Dick Grayson, a circus acrobat whose parents were killed by a mobster before Batman took him in as his ward. Dick was Robin for the longest time of all, before he left the identity to become Nightwing when he stepped out into his own identity.

Next was Jason Todd, who pre-crisis was a redheaded circus acrobat whose parents were murdered by Killer Croc. After the Crisis on Infinite Earths, Jason was turned into a bitter street tough. Batman found him trying to steal the tires off the Batmobile. He was widely disliked, and The Joker beat him to death. He came back to life as the Red Hood (first as a villain and later as an anti-hero).

Boy detective Tim Drake was next. He figured out Batman's secret identity, and joined him as the new Robin.

Number four, Stephanie Brown, lasted only a short time before the Black Mask tortured her to death. She's back now, though.

Five, Damien Wayne, is the son of Bruce Wayne and Talia Al Ghul, and was taken in by his father after his existence was discovered.