Henry Rollins in Johnny Mnemonic. Dude had to play a super nerdy doctor, basically a wet noodle. Let's cast a guy with a nine inch neck and could actually water his way through most of the bad guy minions.

Ryan Gosling in the upcoming Project Hail Mary

I'm sure it'll be fine, but that casting choice wouldn't have been my first pick.

In Don't Look Up, DiCaprio's character is shown getting into flame wars on the internet, and that struck me as something that a professional astronomer would be above.

This is Keanu in Chain Reaction all day long and all night. See also Keanu in The Watcher for least convincing serial killer.