- COCHFARF - see THOMAS, EDWARD
- COFFIN, WALTER (1784 - 1867), colliery pioneer
- COKE, THOMAS (1747 - 1814), Wesleyan Methodist minister
- COLEMAN, DONALD RICHARD (1925 - 1991), Labour politician
- COLLEN (fl. 600?), saint
- COLLINS, WILLIAM LUCAS (1815 - 1887), cleric and author
- COMBERMERE, 1st Viscount - see COTTON, Sir STAPLETON
- COMBERMERE, 6th Baronet - see COTTON, Sir STAPLETON
- COMBERMERE, Baron - see COTTON, Sir STAPLETON
- CONDRY, WILLIAM MORETON (1918 - 1998), naturalist, conservationist and writer
- Congo House / African Training Institute family, students
- CONSTANTINE, GEORGE (c . 1500 - 1560?), cleric
- CONWAY family Botryddan, Bodrhyddan,
- CONWAY, CHARLES (1820 - 1884), painter and engraver
- CONWAY, CHARLES (fl. 1870), water-colour painter and etcher - see CONWAY, CHARLES
- CONWAY, JOHN (c.1545 - 1606), high sheriff - see CONWAY
- CONWY, Botryddan - see CONWAY
- CONYBEARE, WILLIAM DANIEL (1787 - 1857), geologist and divine
- COOK, ARTHUR JAMES (1883 - 1931), miner and trade union leader
- COOMBE TENNANT, WINIFRED MARGARET (Mam o Nedd; 1874 - 1956), delegate to the first assembly of the League of Nations, suffragette, Mistress of the Robes of the Gorsedd of the Bards, and a well-known medium
- COOMBES, BERT LEWIS (1893 - 1974), coal miner and writer
- COPPACK, MAIR HAFINA (1936 - 2011), author and columnist
- COR Y CYRTIE - see JONES, EDWARD
- CORBET, Ynysymaengwyn - see WYNN
- CORBET, Sir RICHARD (1640 - 1683), baronet and member of parliament
- CORBETT, JAMES ANDREW (1846 - 1890) - see CORBETT, JOHN STUART
- CORBETT, JOHN STUART (1845 - 1921), solicitor and antiquary
- CORFANYDD - see WILLIAMS, ROBERT HERBERT
- CORY family
- CORY family
- COSLET, EDWARD (1750 - 1828), Calvinistic Methodist preacher
- COSLETT, COSLETT (Carnelian; 1834 - 1910), collier and poet
- COSLETT, WILLIAM (1831 - 1904), colliery official - see COSLETT, COSLETT
- COTTON, JAMES HENRY (1780 - 1862), dean of Bangor cathedral and educationist
- COTTON, JOHN, printer - see EDDOWES, JOSHUA
- COTTON, Sir STAPLETON (6th baronet, 1st viscount Combermere), (1773 - 1865), field-marshal
- COX, ARTHUR HUBERT (1884 - 1961), geologist
- COX, JOHN (1800 - 1870), printer, bookseller, and postmaster
- COX, LEONARD (fl. 1524-72), schoolmaster and author
- CRADOC, WALTER (1610? - 1659), Puritan theologian
- CRADOCK, Sir MATHEW (1468? - 1531), royal official in South Wales
- CRADOCK, MATHIAS - see CRADOCK, MATHEW
- CRADOCK, RICHARD (fl. 1660-90), Nonconformist preacher, of the Independent persuasion
- CRAIGFRYN - see HUGHES, ISAAC
- CRANOGWEN - see REES, SARAH JANE
- CRAWLEY, RICHARD (1840 - 1893), scholar
- CRAWSHAY family, industrialists Cyfarthfa
- CRAWSHAY, Sir GEOFFREY CARTLAND HUGH (1892 - 1954), soldier and social benefactor
- CREIDIOL - see JENKINS, JABEZ EDMUND
- CREUDDYNFAB - see WILLIAMS, WILLIAM