Alexander Povetkin has defeated four: Byrd, Chagaev, Huck and Rahman. One of those was a cruiserweight champion. Anthony Joshua has defeated three world titleholders, one of which was linear and Ring heavyweight champion: Parker, Povetkin, and Klitschko. Tyson Fury has (officially) defeated one, a linear and Ring champion : Klitschko. He perhaps should have two on his resume, many thought he deserved to win a decision over Wilder. Deontay Wilder has beaten two old former titleholders: Stiverne, who only ever beaten Arreola for a vacant belt, and shot-to-pieces Lyakhovich, who had lost 4 of his previous 6 fights, 3 by KO/TKO. Dillian Whyte has a win over one former titleholder, Joseph Parker. Are there any other currently active heavyweights who have wins over former world titleholders or champions?