My favorite action actor of all time is Arnold Schwarzenegger. I have seen most of his action movies and even though a lot of people make fun of his accent and lack of complete statements, his action moves were awesome. Here's a rundown of some of my favorite movies of his:
Terminator 1,2 and 3
Commando
Total Recall
Predator
Conan the Barbarian
Last Action Hero
True Lies
Six Days
End of Days
Batman and Robin (Mr. Freeze)
Eraser
I have to agree that Arnold is one of the best.
My new favourite is Dwayne Douglas Johnson a.k.a "The Rock". This guy definately has the charisma to go all the way to the top. His movies have done really well so far. I think we'll be seeing a lot more of this guy.
As he would say, "Can you smell what the Rock is cooking"
I am torn between a number of them, but I must admit that Arnold is the best. I also consider Jean Claude Van Damne (Cyborg, Blood Sport) and Keanu as his role in Neo, but outside of that I guess not.
I would say Tom Cruise. He's a really good actor and has participated in other genres except for Action (Rain man, for example.) And he tends to bring into his action movies some more other than pure action, which is always nice to have.