- AP FFARMWR - see JONES, JOHN OWEN
- AP GLASLYN - see OWEN, RICHARD JONES
- AP GWARNANT - see WILLIAMS, THOMAS OSWALD
- AP GWYNN, ARTHUR (1902 - 1987), librarian and the third librarian of the University College of Wales, Aberystwyth
- ap HARRY, BLANCHE - see PARRY, BLANCHE
- AP HEFIN - see LLOYD, HENRY
- ap RHYS, PHILIP (fl. 1530) - see PHILIP ap RHYS
- AP ROGER, OWEN - see ROGERS, OWEN
- AP THOMAS, DAFYDD RHYS (1912 - 2011), Old Testament scholar
- AP VYCHAN - see THOMAS, ROBERT
- APARRY, BLANCHE - see PARRY, BLANCHE
- APHARRIE, BLANCHE - see PARRY, BLANCHE
- APPAREY, BLANCHE - see PARRY, BLANCHE
- APPERLEY, CHARLES JAMES (Nimrod; 1779 - 1843), writer on sport
- APPERLEY, WILLIAM WYNNE (d. 1872), Major in the Indian Army - see APPERLEY, CHARLES JAMES
- ARAFON - see WILLIAMS, WILLIAM HUGH
- Archimandrite Barnabas - see BURTON, IAN HAMILTON
- ARFONA - see EDWARDS, THOMAS
- ARFONWYSON - see THOMAS, JOHN WILLIAM
- ARFRYN - see THOMAS, GEORGE ISAAC
- ARLUNYDD PENYGARN - see THOMAS, THOMAS HENRY
- ARMSTRONG-JONES, Sir ROBERT (1857 - 1943), physician and alienist
- ARNOLD family Llanthony, Llanvihangel Crucorney,
- ARNOLD, JOHN (1634), Whig politician - see ARNOLD
- ARNOLD, NICHOLAS (d. 1665), M.P. - see ARNOLD
- ARTHUR (fl. early 6th century?), one of the leaders of the Britons against their enemies
- ARVONIUS - see ROBERTS, THOMAS
- ASAPH (fl. c. 600), reputed founder of the see of St Asaph
- ASAPH - see ROBERTS, THOMAS ROWLAND
- ASAPH GLAN TÂF - see BEYNON, ROSSER
- ASAPH LLECHID - see DAVIES, ROBERT
- ASHBY, ARTHUR WILFRED (1886 - 1953), agricultural economist
- ASHTON, CHARLES (1848 - 1899), Welsh bibliographer and literary historian
- ASHTON, JOHN (1830 - 1896), musician
- ASSER (d. 909), bishop and scholar
- ATKIN, Baron - see ATKIN, JAMES RICHARD
- ATKIN, JAMES RICHARD (1867 - 1944), judge
- ATKIN, JAMES RICHARD (1867 - 1944), lawyer and judge
- ATKIN, LEON (1902 - 1976), minister of the Social Gospel and a campaigner for the underclass in south Wales
- AUBREY, JOHN (1626 - 1697) - see AUBREY, WILLIAM
- AUBREY, THOMAS (1808 - 1867), Welsh Wesleyan Methodist minister
- AUBREY, WILLIAM (c. 1529 - 1595), civil lawyer
- AUBREY, WILLIAM (1759 - 1827), engineer
- AUBREY, WILLIAM - see AWBREY, WILLIAM
- AUGUSTUS, WILLIAM, a prescientific weather forecaster and translator
- AURELIUS CANINUS (fl. 540), prince
- AVAN, Lord of - see MORGAN FYCHAN
- AWBERY, STANLEY STEPHEN (1888 - 1969), politician, local historian and author
- AYLESTONE, Baron - see BOWDEN, HERBERT WILLIAM