- J.R. - see ROBERTS, JOHN
- J.R. TRYFANWY - see WILLIAMS, JOHN RICHARD
- J.W. LLUNDAIN - see WILLIAMS, JOHN
- JAC GLAN-Y-GORS - see JONES, JOHN
- JAC GLANYGORS - see JONES, JOHN
- JACK RUSSIA - see ROBERTS, JOHN
- JACKSON, Sir CHARLES JAMES (1849 - 1923), businessman and collector
- JACOB, HENRY THOMAS (1864 - 1957), minister (Congl.), lecturer, writer and poet
- JACOB, SARAH (1857 - 1869), fasting girl
- JACOB, WILLIAM (1777 - 1845), musician
- JACOBSEN, THOMAS CHARLES ('Tommy Twinkletoes') (1921 - 1973), musician, artist and entertainer
- JAMES, ANGHARAD (fl. 1680?-1730?), poet
- JAMES, CARWYN REES (1929 - 1983), teacher, rugby player and coach
- JAMES, CHARLES (1820 - 1890?), musician
- JAMES, CHARLES HERBERT (1817 - 1890), M.P.
- JAMES, DANIEL (Gwyrosydd; 1847 - 1920), poet
- JAMES, DAVID (Dewi o Ddyfed; 1803 - 1871), cleric and author
- JAMES, DAVID (1863 - 1929), Rugby football players
- JAMES, DAVID (1787 - 1862), musician
- JAMES, DAVID (Defynnog; 1865 - 1928), schoolmaster, educationist, organiser of summer schools, and author
- JAMES, DAVID EMRYS (Dewi Emrys; 1881 - 1952), minister (Congl.), writer and poet
- JAMES, Sir DAVID JOHN (1887 - 1967), businessman and philanthropist
- JAMES, EDWARD (1569? - 1610?), cleric and translator
- JAMES, EDWARD (1839 - 1904), Congregational minister
- JAMES, EVAN (Ieuan ap Iago, Iago ap Ieuan; 1809 - 1878), author of the words of 'Hen Wlad fy Nhadau'
- JAMES, EVAN (d. c. 1920), Rugby football player - see JAMES, DAVID
- JAMES, FRANK TREHARNE (1861 - 1942), solicitor, art connoisseur
- JAMES, HERBERT ARMITAGE (1844 - 1931), cleric and headmaster
- JAMES, HUGH (1809 - 1875), Independent minister - see JAMES, JOHN
- JAMES, ISAAC (1766 - 1840), Calvinistic Methodist preacher
- JAMES, IVOR (1840? - 1909), first registrar of the University of Wales
- JAMES, IVOR BARNOLD ROBERT - see JAMES, IVOR
- JAMES, JAMES (SPINTHER) (1837 - 1914), Baptist historian
- JAMES, JAMES (Iago Emlyn; 1800 - 1879), Congregational minister and poet
- JAMES, JAMES (1760 - 1831), Calvinistic Methodist and afterwards Independent minister
- JAMES, JAMES (Iago ap Iago; 1818 - 1843), poet
- JAMES, JAMES (1833 - 1902), composer of 'Hen Wlad fy Nhadau' - see JAMES, EVAN
- JAMES, JENKIN (1875 - 1949), first secretary of the University of Wales Council, and author
- JAMES, JOHN (1779 - 1864), the first Unitarian minister in Cardiganshire, and schoolmaster
- JAMES, JOHN (1777 - 1848), Baptist minister, hymn writer, bookbinder, and printer
- JAMES, JOHN (Ioan Meirion; 1815 - 1851), writer
- JAMES, JOHN (fl. second half of the 18th century and the early part of the 19th), poet and hymnwriter
- JAMES, JOHN (d. 1705), Congregational minister
- JAMES, JOHN (1815 - 1869), poet and hymnwriter
- JAMES, JOHN (1872 - 1934), director of education in Glamorganshire
- JAMES, JOHN LLOYD (Clwydwenfro; 1835 - 1919), Congregational minister and historian
- JAMES, JOSHUA (1665 - 1728), one of the earliest ministers of the Baptists
- JAMES, LEMUEL JOHN HOPKIN (Hopcyn; 1874 - 1937), cleric and antiquary
- JAMES, MARIA (1793 - 1868), poet
- JAMES, OWEN WALDO (1845 - 1910), Baptist minister