From New Zealand I would say:
Michael Jordan and Kobe Basketball is huge in Asia as well as the US, and they're well known throughout most of the developed world. MJ has the shoes and the brand, but Kobe is more contemporary.
Yao Ming. Basically have basketball fans from the US and rest of the world + all of China.
Sachin Tendulkar. Everyone in India and anyone that has a passing interest in Cricket. That includes people from Aus, NZ, England, SA, WI, Sri Lanka, Pakistan.
Football wise I'd have though Christiano Ronaldo or Messi just because they're modern players. As someone who doesn't follow football I have hardly heard of Pele or Maradona. I can't imagine that many young kids in less educated parts of the world have either. I understand they're huge.
Suggestions that made me laugh so far: Gretzky, any old US sports people (Jackie Robinson for example, nobody knows who that is, I think that's one of the first black baseball players?).