Today?

Vitali Klitschko is 39, and WBF heavyweight titleholder Evander Holyfield is 47.

Although there was no formal boxing organization until 1921, John L. Sullivan is considered by historians to have been the first heavyweight champion of the world. His reign was between 1882-1892. Click on the 'Heavyweight Boxing Champions' link on this page to see a chronological list of those boxers that have been heavyweight champions.

but muhammed ali is the greastest of all time ha

Either Joe Louis or Max Schmeling. They were both heavyweight champions who faced each other in 1938.

Mike Tyson was 20

Floyd Patterson was 21

Muhammad Ali was 22

The answer depends on what boxing organization you are talking about.

Here is a list of the current (2009) heavyweight champions for the four major sanctioning bodies.

World Boxing Association - Nikolay Valuev

World Boxing Council - Vitali Klitschko

International Boxing Federation - Wladimir Klitschko

World Boxing Organization - Wladimir Klitschko

For updates, see related links below.