He was a terrible Batman. Truly abominable.
Kilmer's reputation for being difficult on set had reportedly exploded into open warfare with the director, Joel Schumacher, normally the most temperate of men, who called his leading man's behaviour "difficult and childish".
John Frankenheimer, who directed Kilmer in The Island of Dr Moreau, was even blunter.
"I don't like Val Kilmer," he said. "I don't like his work ethic and I don't want to be associated with him ever again."
https://www.bbc.com/news/articles/c4n7xy3ew8mo