- GRUFFYDD, IEUAN - see GRUFFYDD, JEREMY
- GRUFFYDD, IFAN (1896 - 1971), author
- GRUFFYDD, JEREMY (fl. middle of the 17th century), poet
- GRUFFYDD, OWEN (c. 1643 - 1730), poet and antiquary
- GRUFFYDD, R. GERAINT - see GRUFFYDD, ROBERT GERAINT
- GRUFFYDD, ROBERT (1753 - 1820), musician
- GRUFFYDD, ROBERT (Patrobas; 1832 - 1863), poet
- GRUFFYDD, ROBERT GERAINT (1928 - 2015), Welsh scholar
- GRUFFYDD, THOMAS (1815 - 1887), one of the best known harpists of his period
- GRUFFYDD, WILLIAM JOHN (1881 - 1954), scholar, poet, critic and editor
- GRYFFYTH, JASPER (d. 1614), cleric, warden of Ruthin hospital, chaplain to archbishop Bancroft, collector of manuscripts
- GUEST family, iron-masters, coal owners, etc.
- GUEST, BERTIE - see GUEST, Lady CHARLOTTE ELIZABETH
- GUEST, LADY CHARLOTTE ELIZABETH (1812 - 1895), translator, businesswoman and collector
- GUNDLEIUS Saint - see GWYNLLYW, Saint
- GUNLYU Saint - see GWYNLLYW, Saint
- GURNOS - see JONES, EVAN
- GUTO NYTH BRÂN - see MORGAN, GRIFFITH
- GUTO'R GLYN (fl. second half of the 15th century), bard
- GUTUN GOCH BRYDYDD (fl. c. 1550?), poet
- GUTUN OWAIN (fl. c. 1460- c. 1498), poet, transcriber of manuscripts, and genealogist
- GUTYN ARFON - see JONES, GRIFFITH HUGH
- GUTYN PADARN - see EDWARDS, GRIFFITH
- GUTYN PERIS - see WILLIAMS, GRIFFITH
- GWAENYSGOR, 1st Baron MACDONALD of - see MACDONALD, GORDON
- GWALCHMAI - see PARRY, RICHARD
- GWALCHMAI ap DAFYDD (fl. 16th century), harpist
- GWALCHMAI ap MEILYR (fl. 1130-1180), court poet
- GWALCHMAI, HUMPHREY (1788 - 1847), Calvinistic Methodist minister
- GWALLTER BACH - see GRIFFITH, WALTER
- GWALLTER DYFI - see REES, EDWARD WALTER
- GWALLTER MECHAIN - see DAVIES, WALTER
- GWALLTER SAIS, landowner - see VAUGHAN
- GWEIRYDD ap RHYS (fl. c. 1170) - see WYNN
- GWEIRYDD ap RHYS - see PRYSE, ROBERT JOHN
- GWEN ferch ELLIS (c. 1552 - 1594), first victim of execution for witchcraft in Wales
- GWENALLT - see JONES, THOMAS MORRIS
- GWENALLT - see JONES, DAVID JAMES
- GWENFFREWI - see GWENFREWI
- GWENFFRWD - see JONES, THOMAS LLOYD
- GWENFREWI (fl. early 7th century), saint
- GWENFREWY - see GWENFREWI
- GWENLLIAN (d. 1136)
- GWENRHIAN GWYNEDD - see BULKELEY-OWEN, FANNY MARY KATHERINE
- GWENT, RICHARD (d. 1543), archdeacon of London
- GWENWYNWYN (d. 1216), lord of Powys
- GWENYNEN GWENT - see HALL, AUGUSTA
- GWERFUL FERCH MADOG - see GWERFUL MECHAIN
- GWERFUL MECHAIN (1462? - 1500), poetess
- GWERFULYN - see JONES, THOMAS ROBERT