1. The most popular version (Also called Nightwing): Dick Greyson
2. The most hated version that most people would rather see murdered and rot in Hell even though he never did anything to provoke such vengeful hostility (Comic Book Readers actually celebrated the day the poor shmuck got murdered by the Joker in the infamous storyline a Death in the Family): Jason Todd
3. The most forgotten: Tim Drake
4. The born out of wedlock son that Bruce Wayne forgot about after having sex with Talia al Ghul (Daughter of Ra's al Ghul) : Damian Wayne
5. The first female version of Robin: Caroline Keene "Carrie" Kelley
6. The second female version of Robin and the third version of Batgirl (Also calls herself the Spoiler) and daughter of Arkham Lunatic Asylum inmate sworn arch enemy Arthur Brown aka the Clue Master (A second rate version of the Riddler) : Stephanie Brown
Carrie Kelley actually never held the job of Robin in the mainstream DC Universe. But rather, Carrie Kelley held the job of Robin in a post nuclear apocalyptic alternate reality version of the DC Universe as seen in the classic mini series The Dark Knight Returns before she became Catgirl in the sequel The Dark Knight Strikes Again. And as long as the DC Universe version of the United States of America was gripped in an oppressive post nuclear apocalyptic dictatorship, Carrie Kelley and Bruce Wayne became close and symbiotic.