That would be American Football.
Soccer
swimming
Probably American football or basketball.
The passionate fan is the Seattle Seahawks
tennis
football or soccer with trillions of fans world wide.
No, football (also known as soccer) is the most competitive sport in the world. It has (by far) the most competitors, the most fans and the most sponsors.
Tennis
Hockey
There is many opinions about that. However the most popular sport is soccer.
The sport that has the most fans is without a doubt, hockey. hockey is the most widely played sport in the world. Just about every country has a hockey team, and other than the U.S., most countries take hockey very seriously. Countries like Brazil, Italy, and Germany are huge hockey fanatics and have thousands and thousands of fans watching.
The most popular sport in the world is football (soccer) football has mass amounts of fans in every continent on the planet and in most countries