Robin was the original superhero sidekick, first introduced in Detective Comics #38 by Bob Kane and Bill Finger in 1940. He was a teenage partner whose parents died at the hands of a mobster that Batman took in, mentoring and training the young hero. That was Dick Grayson, but he was not the first and only Robin in Batman history.
Dick grew up and moved on and others took his place, from a street kid with no parental figures to a detective who found out Batman's secret identity to a girl who decided to take up the mantle after Batman retired. Through it all, Robin was the most important Bat-Family member. Not all these Robins were created equally, and some of them fell short of the mark when it came to which Batman sidekick was best.
Jason Todd
Jason Todd was one of the worst Robin's in comic book history. He was so hated that DC had a fan vote for whether Joker should kill Robin, and the fans voted to let the Boy Wonder die. While that fan vote was disputed, there was no doubt that fans didn't like Jason Todd when he replaced Dick Grayson. The death of Robin ended up as one of the most brutal moments in Batman comics, and some fans reevaluated Jason after that.
Jason was a street kid that Batman took in, but he was one who refused to listen to Batman and did what he wanted no matter the cost. He returned from the dead and became Red Hood, a much better character for Jason than Robin ever was.
Stephanie Brown
Stephanie Brown was the most tragic Robin in DC Comics. She really wanted to be Robin, but at the time Batman didn't want to mentor a new sidekick. He finally relented but put Stephanie in a situation she never had a chance to succeed in. He gave her strict rules and had a zero-tolerance policy.
When Stephanie broke one of the rules to try to do some good, Batman fired her on the spot. She went out to redeem herself and Black Mask tortured and killed her.
Joel Schumacher's Robin
There were a lot of things wrong with the Joel Schumacher Batman movies, with Batman & Robin a low point in the movie franchise. However, one thing that wasn't that bad was Chris O'Donnell's Dick Grayson in Batman Forever. He played the role straight, similar to the comics as a boy who lost his parents and then found his place with Batman.
O'Donnell spoke on the Batman & Robin DVD special features about how he hated that movie, but he did what he could to bring the comic book version of Robin to the big screen in a respectable way.
Helena Wayne
Most fans know Helena Wayne as the original Huntress. She was born on Earth 2 as the daughter of Bruce Wayne and Selina Kyle who grew up to become a superhero. She took on the role of Robin on Earth-2 and fought by her father's side until he died while fighting Parademons.
She ended up on Prime Earth, where she became Huntress with her close friend Supergirl, who changed her name to Power Girl. The Huntress in DC now is not the same character as this original version.
Duke Thomas
Duke Thomas made his debut during the We Are ... Robin storyline where young vigilantes in Gotham City began taking on the role of Robin, leading to the city banning anyone from portraying Robin at all. Of all the new Robins, Duke was the one that mattered.
Duke helped Bruce Wayne in Zero Year, and the only thing that really holds him down was his inability to fit the role of a Batman sidekick, which was important for all Robins. Duke came into his own better when he became The Signal.
Burt Ward's Robin
The first time that fans really got a chance to see Robin in action on the big or small screen was in the 1960s kitschy Batman television series and Batman: The Movie. This Robin was a pure sidekick character to Batman, following his lead and every step.
Many fans love the Adam West and Burt Ward versions of Bartman and Robin, they were mostly played for comedy. In that respect, there weren't very many Robins better at being funny, although that was an acquired taste.
Carrie Kelley
Carrie Kelley became extremely popular thanks to her taking over the Robin role in The Dark Knight Returns by Frank Miller. This was the story taking place in the dystopian future where Batman had retired and crime overran Gotham City. When he returned to try to fight crime again, the GCPD and Superman had to try to stop him.
Carrie took the bad points of some Robins, like Jason Todd and Damian Wayne's snarky attitudes, and she actually made it work for her. She wouldn't quit and was exactly the Robin that Batman needed in this world. It is just too bad she never joined the main DC continuity.
Damian Wayne
When Damian Wayne first showed up, people hated him. He was Bruce Wayne's son with Talia al Ghul and seemed to share much of his grandfather Ra's al Ghul's bloodlust, making him a stark contrast to his father. He was also insolent, spoiled, and arrogant, refusing to play well with others and showing no respect to those around him.
However, slowly Damian opened up and became more of a hero. He tried to be more like his father and his high point came when he worked with Dick Grayson as Batman instead of his father. Damian has developed into a great Robin on his own, leading the Teen Titans and proving to be a true hero.
Tim Drake
When it comes to detective skills, Tim Drake is not only the best Robin but also rivals Batman himself. Unlike the other Robins, who Batman took in after they suffered great losses, Tim used his detective skills to figure out who Batman really was and then used that to basically apply for the role of Robin.
Drake was one of the best Robins as a sidekick, but also as a partner to Batman, second to only Dick Grayson. The only thing that hurt his popularity was that he was too great at times. He went on to become Red Robin and then simply Drake.
Dick Grayson
The best Robin in Batman comics was the original, Dick Grayson, who became Nightwing, one of DC's most wholesome heroes. It was hard for all that followed because they all had to match up to what Dick did before them, and he was the perfect Batman sidekick. He was loyal, determined, and a quick learner. He was also one of the only Robins to ever outgrow the role and become an even bigger hero.
At one point, Dick Grayson took Bruce Wayne's place as Batman. When Dick was Batman's successor and Damian Wayne was Robin, he proved why he was the best Robin ever by mentoring the child in a way superior to even Bruce Wayne.