WHAT WAS THE PLAN? At the beginning of the 1990s when Batman: The Animated Series was in production the plan was for Rocky Horror Picture Show actor Tim Curry to voice Batman's notorious enemy the Joker. OH. SO WHAT WOULD HAVE HAPPENED? By voicing the Joker on Batman: The Animated Series, Curry would have portrayed one of the most iconic super villians in comic-book history and would have appeared in numerous episodes of one of the most highly regarded superhero cartoons ever made. As well as appearing in Batman: The Animated Series Curry would have also voiced the Joker in subsequent spin-off shows and movies all appearing in DC's Animated Universe.
BUT WHAT DID HAPPEN?
Curry was cast as the Joker and provided voice over recordings for a couple of episodes but struggled to maintain the Joker's voice for long periods at a time. Meanwhile Star Wars actor Mark Hamill was cast in a one-off role in the Mr. Freeze-centric episode, Heart Of Ice, where he impressed producers in what was quite a limited role. With producers considering to replace Curry, Hamill was offered the chance to try out for the role and upon hearing his take on the Joker, producers quickly offered him the part.
Hamill's portrayal of the Joker became so popular that he voiced the character in numerous episodes of Batman: The Animated Series, as well as in spin-off movies and connected series'. Hamill also reprised the role of the Joker for a brief cameo in short-lived live-action show Birds Of Prey (2002), as well as in computer games Arkham Asylum (2009) and Arkham City (2011), and for a story board recreation of a deleted scene from Batman (1989) in a special edition DVD release of the film.
SO IT WASN'T A BAD THING THAT CURRY WAS REPLACED THEN?
Nope. For the record, Mark Hamill IS the Joker!
Although Tim Curry is a legend in his own right and has had a very extensive voice over career, the correct decision was made by giving Hamill the role.
BUT WHAT IF?
If Tim Curry had remained in the role of the Joker, Hamill would have missed out on twenty years of regular work as the Clown Prince Of Crime. This could have possibly led him to consider appearing in a Star Wars related show/film/holiday special and it would have ruined the Star Wars franchise forever.
Well, until Star Wars Episode I: The Phantom Menace (1999) was released that is.