Michael Jackson indeed seems to be the most well-known or widely known "name" after he became famous. We can't just say he is the most famous man of all time..because no body knew about him before he was famous, and there are individuals (or god?) like Buddha and Jesus who have been famous for decades of centuries..But, well after he became famous, I don't know about the person, but seems like his name has penetrated most corners of the world..And, he is not limited to English..Dance and music can easily penetrate language barriers..most people here are limiting his popularity to English language; but, as far as I know he is equally well known for his dances..So, any kid, soldier, terrorist, doctor or old lady would compare anybody dancing well to Michael Jackson..and these people are found in anywhere in the world, whether Nepal or South America..I  think he is way more popular than Maradona, Pele or Mike Tyson although they are very popular too. Many people even don't know the person Micael Jackson but know the name..MJ is an icon of the pop culture.