Who was the tallest boxer of all time?

George Mitu 7ft 4in (Romanian)

Jim Cully 7ft 4in (Irish) Boxrec has him listed at 7′ 2″

John Rankin 7ft 4in (American) Boxrec has him listed at 7′ 4"

Väinö Myllyrinne (finland) 8ft 2in.