Vladimir Klitschko is the IBF, WBO, WBA and IBO champion
Vitali Klitschko is the WBC champion
Jack Johnson
There has never been one.
joe louis
Jack Johnson, in 1908,
The boxing instructor was formerly the heavyweight champ.
Among heavyweights, it's Rocky Marciano, followed by current heavyweight champ Vitali Klitschko. What about Lamar Clark?
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.
Joe Louis was champ from 1937 - 1949
kane
Manny Pacquiao
george foreman
The Brown Bomber himself Joe Louis.