Three "tough guys" come to mind:

Steven Seagal
Sylvester Stallone
Arnold Schwarzenegger

For some reason, I've started to believe that Keanu Reeves, Nicholas Cage and David Caruso (who have all been involved in some good movies / TV shows) can't really change the way they act, and have just more or less accidentally ended up in the "right" roles in movies / TV shows that match their personailities.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram