John Rawson, 1st and only Viscount Clontarf (c. 1470–1547) was an English-born statesman in sixteenth-century Ireland, and was regarded as one of the mainstays of English rule in the Kingdom of Ireland. He was the last Prior of the Kilmainham house of the Order of St. John of Jerusalem. The Knights Hospitaller, as they were usually known, were a fighting order of monks, and Rawson himself was an experienced soldier who took part in the Siege of Rhodes (1522). Despite taking holy orders, he was not celibate, and he fathered several illegitimate children. At the Reformation, with no apparent reluctance, he surrendered all his Order's properties to the English Crown in return for a pension and the title of viscount.