When I was posing the question for anyone (dead or alive), I reckoned up the world in vague sections: China; USA/Europe/Russia; Indonesia and other Asia; Indian/Subcontinent; all Africa and middle East; and then South America and left-overs. I realised I knew very little about 5/6 of the world, and guessed people in those sections would not necessarily know more about the west. So I'd guess the "most famous" is whoever in the USA is also known the most in India and China, or whoever in China is also known in the others, etc. Obviously a famous US president is a likely candidate, as is the pope, but i don't know for sure.