Samuel L Jackson is the coolest living person in the world today.
His on screen persona is cool. His off screen persona is cool. He's starred in some of the coolest fims of the last 20 years. He looks cool all the time (who else could pull off a Kangol hat & plaited beard?). Will smith is pretty cool yes, but Sam L is ice cold.
And I can't believe nobody has mentioned Brad Pitt. He's pretty damn cool, more so than Will Smith nowadays (his Mrs is a bit cookoo, but what the hey).