Answer: Tim Curry
During the casting of the 1989 live-action Batman film, Tim Curry was considered for the role of The Joker. While the role in the live-action film went to Jack Nicholson (a role he received enormous critical acclaim for), Curry had his chance at playing The Joker once more in 1992—albeit in a slightly different context.
Curry was the original voice of The Joker in Batman: The Animated Series, but after recording the initial episodes and screen testing them with audiences, Curry was cut from the cast. The reason? His portrayal of The Joker was extremely unnerving to the children in the audience. His distinct voice and intensity were perhaps a bit too much for even the over-the-top Joker character.
Batman: The Animated Series might have been dark, gritty, and compelling for a children’s animated series, but at the end of the day, it was still a show for kids and terrifying the target audience right out of the door was bad for business. Curry was replaced with Mark Hamill, who went on to voice The Joker for the rest of the series as well as in multiple Batman animated films and video games.