Sergey kovalev pretty intimidating I think. a lot of people would of tough guys on here would definitely have called him out on that t-shirt though, because ESB is a site full of real hardcases.
Liston is sort of like Paul Williams. Williams is one of my favorite boxers ever, don't get me wrong. Nonetheless true.
Way before my time but I've read Jack Johnson was pretty intimidating. Tyson and Foreman has to be up there.