What active fighters have the toughest resumes?

[White_Knight]

Everett "Bigfoot" Martin has taken on some challenges over the years:

Dwight Muhammed Qawi
George Foreman
Pierre Coetzer
Bonecrusher Smith
Michael Moorer
Riddick Bowe
Tim Witherspoon
Tony Tucker
Larry Holmes
Herbie Hide
Tony Tubbs
Lance Whitaker
Wladimir Klitschko (x2)
Lamon Brewster
Ruslan Chagaev

[M Bison]

Sven Ottke and Joe Calzaghe.