11. Bob Sapp (19 losses)
Bob Sapp is still a very popular fighter in Japan, as seemingly nobody cares that he loses most of his fights.
Sapp, who has dabbled in pro wrestling as well, has an 11W-19L record. Between 2005 and 2011 he lost 9 straight fights, but that never stopped any promoters from booking him and his freakishly marketable appearance.
He is still under contract with Rizin, and we could see him fight again for the promotion before 2016 is done.
