Valentino rossi
David Foster
It is impossible to quantify who the "most know sportsman in the world" currently is. At one time that title could have easily been given to boxer Muhammad Ali. Michael Jordan is still recognized around the world, as is Lionel Messi, Tiger Woods, and many other superstars.
tiger woods
ruling most of the world in the 1800s
arshavin
Emma morphew
Heng Dong Xin
Probably David Beckham or Tiger Woods
Roger Federer
The popularity of people can ben measured by search queries in Google.trends and the popularity in international media by marshallindex which is measuring how often the name is mentioned in media.In this way you can find out who was most the most famous sportsman at what time, I prefer marshallindex over trends because media has still more impact for celebrities then search.
Valentino rossi
Alexander Karelin could possibly be it.
Afridi
David Foster
queen and royal family mp's and pm sportsman e.g. gerrard, pieterson
criketer Komal Pandey