- TREFÎN - see PHILLIPS, EDGAR
- TREFOR, JOHN, poet - see SION TREFOR
- TREGELLES, SAMUEL PRIDEAUX (1813 - 1875), Biblical scholar and linguist
- TREGONING, WILLIAM EDWARD CECIL (1871 - 1957), industrialist
- TREHARNE, BRYCESON (1879 - 1948), musician
- TREHARNE, REGINALD FRANCIS (1901 - 1967), Professor of history
- TREHERNE, GEORGE GILBERT TREHERNE (1837 - 1923), antiquary
- TREVITHICK, RICHARD (1771 - 1833), engineer
- TREVOR family Trevalun, Plas Têg, Glynde,
- TREVOR family Brynkynallt,
- TREVOR, Sir CHARLES GERALD (1882 - 1959), inspector of forests
- TREVOR, JOHN (d. 1410), bishop of St Asaph
- TREVOR, JOHN (d. 1357), bishop of St Asaph
- TREW, WILLIAM JOHN (1878 - 1926), Wales and Swansea rugby centre three-quarter
- TRITHYD - see DAVIES, THOMAS
- TROY, BLANCHE HERBERT (LADY TROY), (d. c. 1557), Lady Mistress of Elizabeth I, Edward VI and Queen Mary
- TROY, LADY - see TROY, BLANCHE HERBERT
- TRUBSHAW, Dame GWENDOLINE JOYCE (1887 - 1954), public administrator and social worker;
- TRUEMAN, Sir ARTHUR ELIJAH (1894 - 1956), Professor of geology
- TUCKER, JOSIAH (1712 - 1799), cleric and economist
- TUDNO - see JONES, THOMAS TUDNO
- TUDOR family Penmynydd,
- TUDOR, EDMUND (c. 1430 - 1456)
- TUDOR, HENRY - see HENRY VII
- TUDOR, JASPER (c. 1431 - 1495), earl of Pembroke
- TUDOR, OWAIN - see OWAIN TUDOR
- TUDOR, OWEN DAVIES (1818 - 1887), legal writer
- TUDOR, OWEN - see OWAIN TUDOR
- TUDOR, STEPHEN OWEN (1893 - 1967), minister (Presb.) and author
- TUDUR ALED (fl. 1480-1526), poet
- TUDUR CLWYD - see FRIMSTON, THOMAS
- TUDUR GOCH (fl. during Edward II's reign), soldier - see GLYN
- TUDUR PENLLYN (c. 1420 - c. 1485-90), bard
- TURBERVILL, EDITH PICTON - see PICTON-TURBERVILL, EDITH
- TURBERVILLE family Coity,
- TURBERVILLE family Crickhowell,
- TURBERVILLE, EDWARD (c. 1648 - 1681), informer
- TURNBULL, MAURICE JOSEPH LAWSON (1906 - 1944), cricketer and rugby player
- TURNER, EDWARD (1792 - 1826), prize-fighter
- TURNER, ERNEST RICHMOND HORSFALL - see HORSFALL TURNER, ERNEST RICHMOND
- TURNER, Sir LLEWELYN (1823 - 1903) - see TURNER, WILLIAM
- TURNER, MERFYN LLOYD (1915 - 1991), social reformer and author
- TURNER, NED - see TURNER, EDWARD
- TURNER, SHARON (1768 - 1847), solicitor and historian
- TURNER, WILLIAM (1766 - 1853), pioneer of the North Wales slate industry
- TURNOR, DAVID (1751? - 1799), cleric and agriculturist
- TWISLETON, GEORGE (1618 - 1667), officer in the parliamentary army
- TWISTON-DAVIES, LEONARD - see DAVIES, Sir LEONARD TWISTON
- TWM CARNABWTH - see REES, THOMAS
- TWM CHWARAE TEG - see WILLIAMS, THOMAS