Is Val Kilmer to Bruce Wayne what George Lazenby is to James Bond?
In that he inherited an iconic role (with Michael Keaton in this case, being Sean Connery) that served as their big break of sorts (unlike Lazenby, Kilmer was already known before he got the Batman role, but it just seemed like Batman for all intents and purposes, officially solidified Kilmer as an A-list player), but instead of appreciating it, he believed his own hype, and pissed away his career in the process.
https://lebeauleblog.com/?s=val+kilmer