In 1939, Batman first appeared. During that year, Batman was on his own. The next year, Batman was given a sidekick, Robin, the boy wonder. Robin quickly became a prominent character in the Batman franchise. Robin didn't appear in either of the Batman films directed by Tim Burton. There were plans to have Robin in the 1st film, but he ended up being cut out. History repeated itself with the 2nd film. Robin doesn't appear in Batman V Superman or Justice League, because he was murdered by the Joker, offscreen.

Here's a list of the actors who have played Robin in live action:

Douglas Croft in 1943's Batman movie serial

Johnny Duncan in 1949's Batman movie serial

Burt Ward in the 1966 Batman television series and movie, 1979's Legends of the Superheroes 2 part TV special, a cameo in 2019's Crisis on Infinite Earths TV special

Chris O'Donnell in 1995's Batman Forever movie and 1997's Batman and Robin movie

Joseph Gordon Levitt played a character based on Robin in 2012's The Dark Knight Rises movie

Brenton Thwaites played Robin in 2018's Titans series