Ivanson Ranny "Johnny" Nelson (born 4 January 1967) is a British retired professional boxer who competed from 1986 to 2005. He is currently the longest reigning world cruiserweight champion of all time, having held the WBO title from 1999 to 2005.
Nelson defended the title against thirteen different fighters, more than any other cruiserweight in history, and holds a joint-record of most consecutive cruiserweight title defenses (along with Marco Huck). Nelson also held the British cruiserweight title twice between 1989 and 1997, and the European cruiserweight title twice between 1990 and 1998. As of April 2020, BoxRec rates him the greatest cruiserweight of all time.