Worldwide, it would be football (soccer).
The least popular sport is volleyball i checked 100 sites no lie x
The least popular Olympic sport is football.
World=Soccer United States=Baseball
marbles, which is actually a sport
basketball.
Generalizing would be wrong. Every country has a popular sport and an uncommon (even obscure) sport.
Seal clubbing.
curling
probably basketball
cricket :D
Seal clubbing.