- S.M.S. - see SAUNDERS, SARA MARIA
- S.R. - see ROBERTS, SAMUEL
- SALESBURY, Lleweni - see SALUSBURY
- SALESBURY, Rug, Bachymbyd - see SALUSBURY
- SALESBURY, HENRY (1561 - 1637?), grammarian
- SALESBURY, WILLIAM (1520? - 1584?), scholar and chief translator of the first Welsh New Testament
- SALISBURY, Lleweni - see SALUSBURY
- SALISBURY, ENOCH ROBERT GIBBON (1819 - 1890), lawyer and bibliophile
- SALISBURY, HENRY - see SALESBURY, HENRY
- SALISBURY, JOHN (fl. 1695), printer - see SALISBURY, THOMAS
- SALISBURY, PHILIP (d. 1906), soldier - see SALISBURY, ENOCH ROBERT GIBBON
- SALISBURY, THOMAS (1567? - 1620), publisher
- SALMON, DAVID (1852 - 1944), training college principal
- SALMON, HARRY MORREY (1891 - 1985), conservationist, naturalist, soldier
- SALTER DAVIES, ERNEST (1872 - 1955), educationalist
- SALUSBURY, Sir CHARLES JOHN (1792 - 1868), cleric and antiquary
- SALUSBURY, JOHN (1575 - 1625), Jesuit and scholar
- SALUSBURY, PIERS Rûg (fl. early 16th century) - see WYNN
- SALUSBURY, ROBERT Rûg (fl. c. 1549) - see WYNN
- SALUSBURY family Rug, Bachymbyd,
- SALUSBURY family Lleweni, Bachygraig,
- SALUSBURY, THOMAS (1561 - 1586), conspirator
- SALUSBURY, Sir THOMAS (1612 - 1643), poet and country gentleman
- SAMSON (c. 485 - 565), abbot and bishop in the Celtic Church
- SAMUEL, CHRISTMAS (1674 - 1764), Independent minister
- SAMUEL, DAVID (Dewi o Geredigion; 1856 - 1921), schoolmaster and writer
- SAMUEL, DAVID - see SAMWELL, DAVID
- SAMUEL, EDWARD (1674 - 1748), cleric, poet, and author
- SAMUEL, HOWEL WALTER (1881 - 1953), judge and politician
- SAMUEL, WILLIAM THOMAS (1852 - 1917), musician
- SAMUEL, WYNNE ISLWYN (1912 - 1989), local government officer, Plaid Cymru activist and organiser
- SAMWEL, DAVID - see SAMWELL, DAVID
- SAMWELL, DAVID (1751 - 1798), naval surgeon and poet
- SANDBROOK, JOHN ARTHUR (1876 - 1942), journalist
- SANDERS, IOAN (fl. 1786), Methodist exhorter and hymn writer
- SANKEY of MORETON, Viscount - see SANKEY, JOHN
- SANKEY, Baron - see SANKEY, JOHN
- SANKEY, JOHN (BARON SANKEY, VISCOUNT SANKEY of Moreton), (1866 - 1948), lawyer
- SARNICOL - see THOMAS, THOMAS JACOB
- SARTORIS, ADELAIDE (1814? - 1879), singer - see KEMBLE, CHARLES
- SAUNDERS, DAVID (1831 - 1892), Calvinistic Methodist minister, preacher, educationist, and defender of Protestantism
- SAUNDERS, DAVID (Dafydd Glan Teifi; 1769 - 1840), Baptist minister, poet, and writer
- SAUNDERS, DAVID (d. 1812), pastor - see SAUNDERS, EVAN
- SAUNDERS, ERASMUS (1670 - 1724), divine
- SAUNDERS, EVAN (d. 1742), deacon
- SAUNDERS, SARA MARIA (1864 - 1939), evangelist and author
- SAUNDERS, THOMAS (1732 - 1790), Independent minister
- SAUNDERS, WILLIAM (1806 - 1851), poet and writer
- SAUNDERS, WILLIAM (1871 - 1950), minister (B) and educationalist
- SAUNDERSON, CHARLES (1810? - 1832), poet - see SAUNDERSON, ROBERT