Bruce Lee. Not 100% on what is fact and what is fiction about the guy but he made his on screen fights look real and the way he approached his training felt like a precursor to modern MMA
Jason Statham. Has that look that says "come and have a go if you think you are hard enough". Or maybe sings, seeing as that's a Robbie Williams lyric.
Dwayne "The Rock" Johnson. The man has almost always looked like a superhero come to life, and seems custom built to be a modern action movie star.
Honourable mention - Danny Trejo.