David Jones (1 April 1871 – 23 November 1899) who fought under the name Dai St. John was a Welsh heavyweight boxer. In a time before regulated championship titles, St. John used the press to proclaim himself as heavyweight champion of Wales after beating John O'Brien, a fighter he spent his early career building a rivalry against. Despite a high-profile defeat to O'Brien in 1894, St. John continued to fight, but a disastrous contest in which as a cornerman a boxer died at an unsanctioned match saw his career put in jeopardy. A successful period as a sparring partner for Australian champion Peter Jackson revived his career. After joining the British Army, he was posted to South Africa where he fought in the Second Boer World and died in heroic circumstances at the Battle of Belmont.