Challoner (Chaloner, Challyner), John (c.1515–81), merchant and administrator, was second son of Roger Challoner (d. 1521), London alderman, and Margaret Challoner (née Middleton), both of Welsh ancestry. John, sometime auditor in English-occupied Calais, settled in Dublin. As sheriff (1545–6), alderman (1551?–66), mayor (1556–7), farmer of All Hallows (1555–65), and owner of properties in Lambay Island and elsewhere, he belonged to a circle of protestant merchants and civic officials favouring individual enterprise over corporate regulation. In 1559/60 he became MP for Dungarvan. In May 1560, recommended by Sussex (qv), the lord lieutenant, he became secretary of state for Ireland (a newly created office, intended to provide continuous leadership for the administration in Dublin), a member and secretary of the council, and keeper of the signet or privy seal.
Challoner sought several times to be relieved on the grounds of the expenses of office and his own lack of qualification; he carried little weight on the council, lacked close links with English ministers, and suffered ill-health (necessitating the supplementary appointment of Geoffrey Fenton (qv) in 1580). With Challoner's diffidence and the resistance of existing administrative structures, the secretaryship did not become as important as its English equivalent. Challoner was prominent in Dublin reformation politics, serving on the court of high commission (1564) and the commission of ecclesiastical causes (1577). He married first Margaret, daughter of Alderman Walter Fitzsimon; they had a daughter and two sons. He died a.13 May 1581; he and his second wife, Elizabeth Smythe (d. 1585), are buried in Christ Church, Dublin. Luke Challoner (qv) was a nephew.