I know him best from movies like Rocky Horror Picture Show, It, and Home Alone 2: Lost in New York, but actor Tim Curry nearly played another major role when he signed on for the Joker in animated form! According to CBR, Curry weighed in on ultimately missing out on the part during an appearance at a Fan Expo in Canada back in 2017 (listen to the audio clip here) saying he was "fired." Apparently, Curry started work on Batman: The Animated Series but had to be replaced by Mark Hamill due to unforeseen circumstances:
"I did play Joker for a while, but I had bronchitis and they fired me, and hired Mark Hamill. That’s life."- Tim Curry
Ruthless! Hamill is well known for his voice work on Batman: The Animated Series and other DC titles, and many would say he's perfect for the part. I'm sure Curry would've done a great job voicing the villain as well, but it was clearly just not meant to be.
Many iconic actors were in the running to play the Joker at some point throughout the years, and Robin Williams is no exception. The late and great comedian was actually offered the part for Tim Burton's Batman, according to Collider, before they decided to go with Jack Nicholson instead. According to the publication, Nicholson was one of the first choices but he did not want to take on the part. So, they turned to Williams.
Per the 2018 book Robin written by Dave Itzkoff (as reported by Collider), Williams was becoming a very successful and popular actor at the time Batman was being developed, having just been nominated for his first Academy Award for his role in Good Morning, Vietnam. Williams was also a Batman fan, making the casting kind of a no-brainer. Williams even accepted the role — though he didn't fully believe it was "sincere" — and Nicholson eventually changed his mind. The studio then went with Nicholson, who they wanted all along. Ouch.