Well, if I was going to try and answer things like this I'd probably be looking beyond actors and into things like the UFC. Of course with all the rules in the UFC nowadays it's hard to say how tough a lot of those guys actually are. Someone like Brock Lesner is actually probably pretty high up there on the "total badass" scale just the same however.
While he's now ancient, you've also got guys like Chuck Merriman who are not only world class fighters, but have travelled all over the world teaching soldiers, security forces, etc. He has a whole chain of fighting schools under him nowadays, I can't say how good they are though because he of course doesn't instruct at all of them.
Chuck Norris is excluded as was mentioned, but all internet jokes aside, the guy was a world champion martial artist for many years, and sparred with Bruce Lee regularly. His friendship there was why Bruce Lee was the only guy he let beat him as a villain in a movie. He had very specific standards about his film career, and how he was going to be portrayed.
All told when it comes to most actors out there, I simply don't know what kind of actual training they have. Acting tough and actually being tough are two differant things.
Steven Seagal and Van Damme are both pretty tough guys by all accounts, with some really serious martial arts training behind them. However I'm not sure how long either of them actually held out titles in competitions. I don't even know if Seagal (sadly I'm ignorant here) ever fought competitively. I remember hearing Van Damme did, but I don't know how long he was at the top of the game, plus with no offense intended he has gotten his butt kicked in some really embarassing situations in the last few years.
Also, laugh if you want, but while not anywhere near the top of his game, Mike Tyson is still one of the people I'd least want to get into a fight with.
