- TAFALAW BENCERDD - see JONES, THOMAS GRUFFYDD
- TAFOLOG - see DAVIES, RICHARD
- TALBOT family Margam Abbey, Penrice Castle,
- TALBOT of HENSOL, 1st Baron - see TALBOT, CHARLES
- TALBOT, CHARLES (1st baron Talbot of Hensol), (1685 - 1737), lord chancellor
- TALHAIARN - see JONES, JOHN
- TALIESIN (fl. second half of the 6th century), bard
- TALIESIN ab IOLO - see WILLIAMS, TALIESIN
- TALIESIN CRAIG-Y-FELIN - see THOMAS, THOMAS EMLYN
- TALIESIN HIRAETHOG - see DAVIES, JOHN
- TALIESIN O EIFION - see JONES, THOMAS
- TANNER, PHILIP (1862 - 1950), folk singer
- TANYMARIAN - see STEPHEN, EDWARD JONES
- TATHAI Saint - see TATHAN, Saint
- TATHAN (fl. 5th century), saint
- TATHEUS Saint - see TATHAN, Saint
- TAU GIMEL - see GRIFFITHS, THOMAS JEREMY
- TAYLOR, HENRY (1845 - 1927), historian and antiquary
- TEGAI - see HUGHES, HUGH
- TEGID - see JONES, JOHN
- TEGIDON - see PHILLIPS, JOHN
- TEGLA - see DAVIES, EDWARD TEGLA
- TEGWYN - see THOMAS DAVIES
- TEILIWR LLAWEN - see GRUFFYDD, JEREMY
- TEILO (fl. 6th century), Celtic saint
- TELFORD, THOMAS (1757 - 1834), civil engineer
- TELYNFAB - see EVANS, BENJAMIN
- TELYNOG - see EVANS, THOMAS
- TELYNOR CYMRU - see ROBERTS, JOHN
- TELYNOR DALL, Y - see ROBERTS, RICHARD
- TELYNOR DALL, Y - see PARRY, JOHN
- TELYNOR MAWDDWY - see ROBERTS, DAVID
- TELYNOR WAUN OER - see JONES, HUGH
- TELYNOR Y GOGLEDD - see DAVIES, JOHN ELIAS
- TELYNORES MALDWYN - see JONES, NANSI RICHARDS
- TEMPLE, ANNE - see HUGHES, HYWEL STANFORD
- TENNANT, WINIFRED MARGARET COOMBE - see COOMBE TENNANT, WINIFRED MARGARET
- THAME, Baron WILLIAMS of (1500? - 1569), custodian of the crown jewels of Henry VIII - see WILLIAMS, JOHN
- THE LUDLOW LAWYER - see GIBBS, SION
- THE MAID OF CEFN YDFA (1704 - 1727) - see MADDOCKS, ANN
- THELWALL family Plas y Ward, Bathafarn, Plas Coch, Llanbedr,
- THELWALL, JOHN (1764 - 1834), reformer, lecturer and poet
- THESBIAD, Y - see ELIAS, JOHN ROOSE
- THICKENS, JOHN (1865 - 1952), minister (Presb.), historian and author
- THIRLWALL, CONNOP (1797 - 1875), bishop of S. Davids
- THODAY, DAVID (1883 - 1964), botanist, university professor
- THODAY, MARY GLADYS (1884 - 1943), scientist, suffragist, peace-campaigner
- THOMAS family Coed Helen (or Alun), Aber,
- THOMAS family Wenvoe,
- THOMAS ab EINION - see THOMAS TEIFI