John Joseph Monaghan was a world flyweight boxing champion from Belfast. He became famous in the post-war period, eventually rising to become undisputed world champion and a hero to many people in his home city.

Born in Lancaster Street in North Belfast, Monaghan attended St Patrick's Christian Brothers' School in Donegall St. A noted fighter at boys' level, he entered the paid ranks in his mid-teens. After a short absence for wartime service, Monaghan resumed his career and his burgeoning reputation drew huge crowds from all parts of his home city. In particular, bouts at Belfast's King's Hall were the highlight with that venue normally packed to the rafters.

In October 1947, the National Boxing Association world crown became his after outpointing the American, Dado Marino at Harringay Stadium for the vacant title. The mantle of undisputed champion of the world rested on his shoulders after his defeat of the tough Scottish fighter Jackie Paterson by knock-out in the King's Hall on 23 March 1948. Paterson was to prove one of the Belfast man's major adversaries.

In April 1949 he retained his World title, and became European champion, by dispatching Frenchman Maurice Sandeyron.

His final fight came in September 1949 when he drew with Londoner Terry Allen. By the time that a long-standing chest complaint forced his retirement as champion in 1950, Monaghan's trophy-cabinet contained the British, European, Commonwealth and World crowns. Of the 66 official bouts he fought during his successful career, he lost only nine and drew six. Monaghan endeared himself to his supporters after his fights by singing 'When Irish Eyes are Smiling' to the King's Hall audience, which joined in the singing.

His nickname "Rinty" came from his fondness for dogs. According to his daughter Martha, he brought home injured dogs so often that his grandmother called him Rin Tin Tin, after the film dog, and shortened it to Rinty.

Belfast City Council erected a statue to Monaghan at Cathedral Gardens on 20 August 2015. Designed by Alan Beattie Herriot, this 10-foot high bronze statue on a granite plinth features Monaghan holding a microphone and singing "When Irish Eyes are Smiling".