- TAFALAW BENCERDD - gweler JONES, THOMAS GRUFFYDD
- TAFOLOG - gweler DAVIES, RICHARD
- teulu TALBOT Abaty Margam, Chastell Penrhys,
- TALBOT o HENSOL, Barwn 1af - gweler TALBOT, CHARLES
- TALBOT, CHARLES (y barwn Talbot o Hensol (sir Forgannwg) 1af), (1685 - 1737), arglwydd-ganghellor
- TALHAIARN - gweler JONES, JOHN
- TALIESIN (fl. ail hanner y 6ed ganrif), bardd
- TALIESIN ab IOLO - gweler WILLIAMS, TALIESIN
- TALIESIN CRAIG-Y-FELIN - gweler THOMAS, THOMAS EMLYN
- TALIESIN HIRAETHOG - gweler DAVIES, JOHN
- TALIESIN O EIFION - gweler JONES, THOMAS
- TANNER, PHILIP (1862 - 1950), ceidwad caneuon a dawnsiau gwerin
- TANYMARIAN - gweler STEPHEN, EDWARD JONES
- TATHAI Sant - gweler TATHAN, Sant
- TATHAN (fl. 5ed ganrif), sant
- TATHEUS Sant - gweler TATHAN, Sant
- TAU GIMEL - gweler GRIFFITHS, THOMAS JEREMY
- TAYLOR, HENRY (1845 - 1927), hanesydd a hynafiaethydd
- TEGAI - gweler HUGHES, HUGH
- TEGID - gweler JONES, JOHN
- TEGIDON - gweler PHILLIPS, JOHN
- TEGLA - gweler DAVIES, EDWARD TEGLA
- TEGWYN - gweler THOMAS DAVIES
- TEILIWR LLAWEN - gweler GRUFFYDD, JEREMY
- TEILO (fl. 6ed ganrif), sant Celtig
- TELFORD, THOMAS (1757 - 1834), peiriannydd sifil enwog a ddechreuodd fel prentis saer maen
- TELYNFAB - gweler EVANS, BENJAMIN
- TELYNOG - gweler EVANS, THOMAS
- TELYNOR CYMRU - gweler ROBERTS, JOHN
- TELYNOR DALL, Y - gweler ROBERTS, RICHARD
- TELYNOR DALL, Y - gweler PARRY, JOHN
- TELYNOR MAWDDWY - gweler ROBERTS, DAVID
- TELYNOR WAUN OER - gweler JONES, HUGH
- TELYNOR Y GOGLEDD - gweler DAVIES, JOHN ELIAS
- TELYNORES MALDWYN - gweler JONES, NANSI RICHARDS
- TEMPLE, ANNE - gweler HUGHES, HYWEL STANFORD
- TENNANT, WINIFRED MARGARET COOMBE - gweler COOMBE TENNANT, WINIFRED MARGARET
- THAME, Barwn WILLIAMS o (1500? - 1569), ceidwad gemau Harri VIII - gweler WILLIAMS, JOHN
- THE LUDLOW LAWYER - gweler GIBBS, SION
- teulu THELWALL Plas y Ward, Bathafarn, Plas Coch, Llanbedr,
- THELWALL, JOHN (1764 - 1834), diwygiwr, darlithydd a bardd
- THESBIAD, Y - gweler ELIAS, JOHN ROOSE
- THICKENS, JOHN (1865 - 1952), gweinidog (MC), hanesydd ac awdur
- THIRLWALL, CONNOP (1797 - 1875), esgob Tyddewi
- THODAY, DAVID (1883 - 1964), botanegydd, Athro prifysgol
- THODAY, MARY GLADYS (1884 - 1943), gwyddonydd, etholfreintwraig, ymgyrchydd heddwch
- teulu THOMAS Coed Alun, Aber,
- teulu THOMAS Wenvoe,
- THOMAS ab EINION - gweler THOMAS TEIFI
- THOMAS ab IEUAN - gweler JAMES, THOMAS EVAN