- CRISTIOLUS MÔN - see HUGHES, DAVID
- CROMWELL O WENT - see JONES, HUGH
- CROPPER, THOMAS (1869 - 1923) Buckley, antiquary
- CROWTHER, JOHN NEWTON (Glanceri; 1847 - 1928), schoolmaster
- CRWYS - see WILLIAMS, WILLIAM CRWYS
- CRYCH ELEN - see LLOYD, THOMAS
- CRYTHOR LLWYD MARCHEDD (fl. 16th century), musician
- CRYTHWR DALL O GEREDIGION - see THOMAS, FRANCIS
- CUDLIPP, PERCY (1905 - 1962), journalist
- CUHELYN - see PRICE, THOMAS GWALLTER
- CUNEDDA WLEDIG (fl. 450?), British prince
- CURIG (fl. 550?), saint
- CYBI (fl. 550), saint
- CYBI - see EVANS, ROBERT
- CYDIFOR (d. 1163), archdeacon - see SULIEN
- CYFEILIOG (d. 927), bishop of Llandaff
- CYFEILLIOG - see CYFEILIOG
- CYFFIN - see JONES, THOMAS GRIFFITHS
- CYFFIN, ROGER (fl. c. 1587-1609), a poet
- CYMRO BACH - see PRICE, BENJAMIN
- CYMRO GWYLLT - see EDWARDS, WILLIAM
- CYNAN - see JONES, Sir CYNAN ALBERT EVANS
- CYNAN ab OWAIN (d. 1174), prince
- CYNAN ap HYWEL (d. 1242?), prince
- CYNAN ap IAGO (d. 1060?), exiled prince
- CYNAN DINDAETHWY (d. 816), prince
- CYNDDELW - see ELLIS, ROBERT
- CYNDDELW BRYDYDD MAWR (fl. 1155-1200), leading 12th century Welsh court poet
- CYNDEYRN, saint
- CYNDEYRN - see DAVIES, ROBERT
- CYNDEYRN Saint - see KENTIGERN, Saint
- CYNFAEN - see EVANS, JOHN HUGH
- CYNFRIG ap DAFYDD GOCH (fl. c. 1420), poet
- CYNGAR (fl. 6th century), saint
- CYNGEN, (d. 855), prince
- CYNHAFAL - see JONES, NATHANIEL CYNHAFAL
- CYNHAIARN - see JONES, THOMAS
- CYNHAVAL - see WILLIAMS, JOHN
- CYNIDR (fl. 6th century), saint
- CYNLLO (fl. 550?), saint
- CYNLLO MAELIENYDD - see EVANS, MORGAN
- CYNLLO MAESYFED - see EVANS, MORGAN
- CYNOG (fl. 500?), saint
- CYNONFARDD - see EDWARDS, THOMAS
- CYNWAL, RICHARD (d. 1634), poet
- CYNWAL, WILLIAM (d. 1587), poet
- CYNWRIG ap RHYS (d. 1237), prince.
- CYNWRIG BENCERDD (fl. 15th century), harpist
- CYNWRIG HIR (fl. 1093) Edeirnion