Bruce Wayne vs. Lex Luthor vs. Tony Stark - The Richest There Is!

Based on displayed showings of wealth, who is the richest one between them? And is the winner the richest character in fiction by default?

McDuck is the richest.

For Lex, Bruce and Tony, probably depends on whos up and whos down any given year. They're all fairly known for losing everything and coming back up.