- JONES-DAVIES, THOMAS ELLIS (1906 - 1960), doctor and international rugby player
- JONES-PARRY, Madryn Llyn - see PARRY
- JONES-PIERCE, THOMAS - see PIERCE, THOMAS JONES
- JOSEFF Y SEINAD - see JONES, THOMAS
- JOSHUA, FRANCIS JAMES (1861 - 1920), minister - see JOSHUA, SETH
- JOSHUA, FRANK (1861 - 1920), minister - see JOSHUA, SETH
- JOSHUA, SETH (1858 - 1925), minister (Presb.)
- JOYCE, GILBERT CUNNINGHAM (1866 - 1942), bishop
- JUSTINIAN SAINT (fl. 6th century)