| Flannagain | A name meaning little red one. |
| Flannagan | Descendant of the red one |
| Flannan | Variant of Flannery: Red-haired. |
| Flannery | Descendant of the red warrior |
| Flinn | Son of a red-haired man. |
| Floinn | An Irish name meaning descendant. |
| Flyn | Son of a red-haired man. |
| Flynn | Son of a red-haired man. Surname. |
| Fogartaigh | One who is an exiled person. |
| Fogarty | Descendant of the banished one. |
| Fogerty | A name meaning exiled person. |
| Foley | A descendant of the plunderer. |
| Forgael | Variant of Fergal: Brave. |
| Fynballa | A name meaning white shoulder. |
| Ga!l | A name meaning a joyful person. |
| Gadhra | One who is dark or dusky in hue. |
| Gaffney | An Irish name meaning calf herder. |
| Gaige | Moneylender, Pledge, Surety |
| Gaile | A name meaning joy or happiness. |
| Gairbith | A name meaning rough existence. |
| Gallagher | Meaning a brave foreigner. |
| Garbhan | A name meaning a little rough one. |
| Garran | Guards: guardian. |
| Garrity | A descendant of the spear. |
| Garry | Diminutive of Gareth: Gentle. Modest and brave Sir Gareth was a legendary knight of King Arthur's Round Table.; Diminutive of Garret: Hard or bold spear. An Irish variant of the German Gerard, based on medieval pronunciation. Famous bearer: Irish statesma |
| Garvan | An Irish name meaning small rough one. |
| Garve | A name meaning rough or rugged. |
| Garvey | A name meaning rough or spear. |
| Garvin | A name meaning rough friend. |
| Gearoid | The Irish form of the name Gerald. |
| Geraghty | An Irish name meaning earless. |
| Geralt | A name meaning spear strength. |
| Gikhrist | A follower of Jesus Christ. |
| Gilbride | Serves Saint Bridget |
| Gildea | Servant of the holy God of light. |
| Gilibeirt | A bright and famous pledge bearer. |
| Gilley | A bright and youthful pledge boy. |
| Gilvarry | A bright, noble warrior. |
| Giollabrighde | Serves Saint Bridget |
| Giollabuidhe | The yellowhaired servant. |