- GWGON ap MEURIG (d. 871), king of Ceredigion, and the last of the line of Ceredig
- GWGON BRYDYDD (fl. c. 1240), poet
- GWILI - see JENKINS, JOHN GWILI
- GWILYM ab ELIS - see ELLIS, WILLIAM
- GWILYM ab IOAN - see WILLIAMS, WILLIAM
- GWILYM ALAW - see OWEN, WILLIAM
- GWILYM AMAN - see JONES, GWILYM RICHARD
- GWILYM ap GRUFFYDD (c. 1370 - 1430) - see GRIFFITH
- GWILYM ap IEUAN HEN (fl. c. 1440-1480), poet
- GWILYM ap IOAN - see WILLIAMS, WILLIAM
- GWILYM ap IORWERTH - see WILLIAMS, WILLIAM
- GWILYM ap SEFNYN, poet
- GWILYM CALEDFFRWD - see GRIFFITH, WILLIAM
- GWILYM CALEDFRYN - see WILLIAMS, WILLIAM
- GWILYM CALLESTR - see EDWARDS, WILLIAM
- GWILYM CANOLDREF - see MIDLETON, WILLIAM
- GWILYM CARADOG - see EVANS, DAVID
- GWILYM COWLYD - see ROBERTS, WILLIAM JOHN
- GWILYM CYFEILIOG - see WILLIAMS, WILLIAM
- GWILYM DDU GLAN HAFREN - see OWEN, WILLIAM
- GWILYM DDU O ARFON (fl. c. 1280-1320), poet
- GWILYM DDU O ARFON - see WILLIAMS, WILLIAM
- GWILYM DEUDRAETH - see EDWARDS, WILLIAM THOMAS
- GWILYM ELIAN - see COSLETT, COSLETT
- GWILYM ERYRI - see ROBERTS, WILLIAM
- GWILYM GARW-DYLE - see HARRI, WILLIAM
- GWILYM GELLI-DEG - see MORGAN, WILLIAM
- GWILYM GLAN LLWCHWR - see OWEN, WILLIAM
- GWILYM GWALSTAWD IEITHOEDD - see THOMAS, WILLIAM
- GWILYM GWENFFRWD - see THOMAS, WILLIAM THEOPHILUS
- GWILYM GWENT - see WILLIAMS, WILLIAM AUBREY
- GWILYM GWYN (fl. end of 15 c.), poet
- GWILYM HIRAETHOG - see REES, WILLIAM
- GWILYM LLEYN - see ROWLANDS, WILLIAM
- GWILYM MAI - see THOMAS, WILLIAM
- GWILYM MARLES - see THOMAS, WILLIAM
- GWILYM MEUDWY - see OWEN, WILLIAM
- GWILYM MORGANNWG - see WILLIAMS, THOMAS
- GWILYM MORGANWG - see WILLIAMS, THOMAS
- GWILYM MYRDDIN - see JONES, WILLIAM
- GWILYM O FEIRION - see PUGHE, WILLIAM OWEN
- GWILYM PADARN - see EDWARDS, WILLIAM
- GWILYM PENNANT - see POWELL, WILLIAM
- GWILYM PERIS - see WILLIAMS, WILLIAM
- GWILYM RHONDDA - see THOMAS, WILLIAM PHILLIP
- GWILYM RYFEL (fl. 12th century), poet
- GWILYM TEILO - see DAVIES, WILLIAM
- GWILYM TEW (fl. c. 1460-1480), one of the bards of Glamorgan
- GWILYM TEW - see MOSES, WILLIAM
- GWILYM TEW O LAN TÂF - see MOSES, WILLIAM