Bruce Lee and Jackie Chan are the greatest and most well known martial artist in the world. They have both amassed millions at the box office and basically anything with their names sells. Movies, posters, t-shirts, calenders, TV shows, etc... Bruce single handedly started the martial arts craze back in the 60's and early 70's and Jackie continues to carry on this legacy in his own unique way. He's still making movies that entertain audiences around the world.
If you want to watch pure rage and see the bad guys really get a whuppin' check out Bruce Lee, but on the other hand if you want to laugh and see some amazing stunts and acrobatics check out Jackie Chan. Some other Martial Artist worth mentioning: Sonny Chiba, Jet Li, Jim Kelly, and Taimak.