There are a lot of famous rabbis, many are regional though.
I would say NO, he isn't the most famous Rabbi, but definitely one of the more known ones in the last two centuries (he died in 1810).
As of 2011, the most famous Sephardi rabbi in Israel is former Sephardi Chief Rabbi of Israel, Rabbi Ovadia Yosef.
Mordecai, in the Book of Esther.
Jesus Christ was the most famous Rabbi. He was Jewish. He had a following of disciples. He taught. He confounded the Rabbis of his day. He is better know that any other Jewish teacher of the Law. Jesus Christ is the most well known of those who claim to be "our Great High Priest" Heb.4:14.
Israel
most likely the RomBom (Rabbi Moshe ben Maimon) otherwise known as maimonidies there was a rabbi after him also in Spain called the RomBon (Rabbi Moshe ben Nachmun) or Nachmonidies, he was pretty famous too
No. In fact, most countries in the world do not have chief rabbis. But if the synagogue has more than 1 rabbi, the Senior Rabbi should be present if possible.
Atlantic Ocean is the most famous ocean in the world.
Shimon sofer was was a famous a rabbi and a member of parliament
The most famous pokemon around the world is Pikachu
A Border Colie there the most famous.
The most famous magician in the world was Harry Houdini.