Irish last names hold centuries of history, reflecting ancient warriors, scholars, and noble families. Some, like Gillespie and Grady, highlight religious devotion, while others, like Gilroy, trace back to fierce Gaelic warriors. But among them, one name stands out for its unique blend of mythology, heritage, and meaning.

Discover the depth of Irish names with our themed collections of first and last names. If you’re curious, we also have a guide to Irish first names beginning with G.

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Authentic Irish Last Names that Start with G

⭐ Our Favourite: Guckian (Mac Oisín)

Pronunciation: GUCK-ian
First recorded: 16th century
Meaning: Mac Oisín means “son of Oisín,” directly linking this last name to one of the most famous figures in Irish mythology. Oisín, son of the legendary warrior Fionn Mac Cumhaill, was a poet and fighter of the Fianna, known for his journey to Tír na nÓg. The Guckian last name originates in Leitrim, where the family was historically associated with storytelling and poetry.
Why it’s our favourite: This name is a rare gem, deeply rooted in Irish folklore. Unlike many last names tied to historical rulers or landowners, Guckian carries a connection to Ireland’s greatest epic tales. It speaks to Ireland’s oral traditions, the heroism of the Fianna, and the mythical lands of eternal youth. It’s a last name with a story—one that feels unmistakably Irish.

🍀 Gallagher (Ó Gallchobhair)

Pronunciation: GALL-uh-her
First recorded: 1022
Region: Donegal
Meaning: Derived from the Gaelic Gallchobhar, meaning “foreign helper” or “lover of foreigners,” the Gallagher family was historically one of the most powerful clans in Donegal. They were hereditary marshals to the O’Donnell chieftains and played a key role in defending the region. The name suggests an early connection with Norse settlers or perhaps aiding foreign invaders. A famous bearer is Rory Gallagher, the legendary Irish blues guitarist, though the name has been carried by many influential figures in Irish history.

🐂 Gannon (Ó Gamhna)

Pronunciation: GAN-un
First recorded: 13th century
Region: Roscommon, Mayo
Meaning: Ó Gamhna means “descendant of the calf,” referring to cattle-rearing, a vital part of medieval Irish life. The name was associated with landowning families who held influence in Connacht, particularly in Roscommon and Mayo. The Gannons were known as a learned family, with records of poets and scribes among them. The name remains popular in Ireland, with variations found in the U.S. due to emigration during the 19th-century Famine.

🏇 Geoghegan (Mag Eochagáin)

Pronunciation: GAY-gun
First recorded: 1170
Region: Westmeath
Meaning: Coming from Eochagán, meaning “horse rider” or “horse-born,” the Geoghegans were a noble family in County Westmeath. They ruled lands around Kilbeggan and were known for their resistance to English rule, particularly during the Tudor conquest of Ireland. Their motto, “Fortis et hospitalis” (Brave and hospitable), reflected their reputation as both fierce warriors and generous hosts. The name is still common in Westmeath, and descendants can be found across the world.

🛡️ Grealish (Griallais)

Pronunciation: GREEL-ish
First recorded: 16th century
Region: Galway
Meaning: This last name has Norman roots, but by the 1500s, it had become firmly associated with Galway’s merchant families. The Grealish name was linked to the ‘Tribes of Galway,’ a group of 14 powerful merchant families who controlled trade in the city. Some theories suggest it originates from a word meaning “valiant” or “noble.” Today, it remains a well-known name in Galway, particularly in politics and business.

🌿 Grealey (Ó Gríalaigh)

Pronunciation: GREE-lee
First recorded: 13th century
Region: Mayo
Meaning: Derived from the Gaelic gríallach, meaning “noble” or “illustrious,” the Grealeys were an old Connacht family, closely linked to the O’Connors. The name appears in medieval land records, showing their role as minor landowners. Over time, the spelling changed, particularly in England and America. Some Grealeys were known for their involvement in literature and arts, though the name remains rare outside Ireland.

⛰️ Glynn (Ó Glinn)

Pronunciation: GLIN
First recorded: 12th century
Region: Galway, Clare
Meaning: Meaning “of the valley” or “deep glen,” the name Ó Glinn refers to someone who lived in or near a valley. The Glynn family was originally associated with the west of Ireland, particularly Clare and Galway. In history, they were minor chieftains, often acting as allies to more dominant families. The name is still found in these areas, and some bearers emigrated to the U.S. and Australia during the 19th century.

📜 Gogan (Ó Gogáin)

Pronunciation: GOH-gan
First recorded: 14th century
Region: Cork
Meaning: This last name’s origins are debated, but some scholars believe it derives from a Gaelic word meaning “little priest” or “devoted one.” The Gogans were a learned family in medieval Munster, known for their scribes and scholars. The name is still found in Cork today, though it is relatively uncommon.

⚔️ Gogarty (Ó Gogartaigh)

Pronunciation: GOH-gar-tee
First recorded: 14th century
Region: Meath
Meaning: The Gogartys were originally a family of poets and physicians in medieval Ireland. The most famous bearer was Oliver St. John Gogarty, an Irish poet and surgeon who inspired the character Buck Mulligan in James Joyce’s Ulysses. The name’s exact meaning is uncertain but may relate to strength or protection. Historically, the family served as hereditary physicians to the O’Neills of Ulster.

🏹 Guinan (Ó Cuanáin)

Pronunciation: GWIN-an
First recorded: 11th century
Region: Offaly
Meaning: Derived from Cuanán, meaning “little warrior” or “protector,” the Guinan family was historically tied to the ancient kingdom of Uí Failghe (modern Offaly). They were respected as warriors and defenders of Gaelic traditions, particularly against Norman invaders. Today, the name is still common in the Midlands, though many Guinans emigrated to America in the 19th century.

⚔️ Gilhooley (Mac Giolla Chomhghaill)

Pronunciation: gil-HOO-lee
First recorded: 12th century
Region: Leitrim, Longford
Meaning: Derived from Mac Giolla Chomhghaill, meaning “son of the servant of St. Comhghall,” this last name reflects a strong religious connection, particularly to St. Comgall, founder of the influential Bangor Monastery. The Gilhooleys were historically associated with the O’Rourkes of Breifne, serving as key allies and landholders. While once prominent in medieval church records, the name became less common over time but remains concentrated in the midlands.

🐺 Gavaghan (Ó Gaibhtheacháin)

Pronunciation: GAV-a-han
First recorded: 13th century
Region: Mayo, Sligo
Meaning: Derived from Ó Gaibhtheacháin, meaning “descendant of the fierce one” or “valiant warrior,” this name suggests a lineage of strong fighters. The Gavaghan clan was closely connected to the O’Dowds of Connacht and played a significant role in defending Gaelic territories from Anglo-Norman incursions. The name is still found in the west of Ireland, with some variations in spelling due to emigration.

⛪ Giltenan (Mac Giolla Tighearnáin)

Pronunciation: gil-TEN-an
First recorded: 14th century
Region: Cavan
Meaning: The name Mac Giolla Tighearnáin translates to “son of the servant of Tighearnán,” referring to devotion to St. Tighearnán, a lesser-known early Christian figure in Ireland. The Giltenans were originally a learned family, known for their association with monastic settlements in Ulster. While never a dominant last name, it has persisted in small numbers, particularly in Cavan and surrounding counties.

🌊 Gilvarry (Mac Giolla Bhearaigh)

Pronunciation: gil-VAR-ee
First recorded: 15th century
Region: Mayo
Meaning: Mac Giolla Bhearaigh means “son of the servant of Bearach,” referring to St. Bearach, a patron of Kilbarron. The Gilvarrys were primarily found along the western coast, often linked to maritime activities. Many members of the family were seafarers and traders, some even becoming pirates along the rugged Atlantic coastline. The name remains most common in County Mayo today.

🍷 Gaynor (Mag Fhionnbhairr)

Pronunciation: GAY-ner
First recorded: 1251
Region: Longford, Westmeath
Meaning: Meaning “descendant of Fionnbharr” (a name meaning “fair-haired”), the Gaynor family was a branch of the McGeoghegans of Meath. They held lands in Longford and Westmeath, often involved in local chieftain politics. Some later became prominent wine merchants in France and Spain following the Flight of the Earls. The name remains well known in midland counties, though variations like “Gainer” appear in North America.

🦅 Griffin (Ó Gríobhtha)

Pronunciation: GRIFF-in
First recorded: 11th century
Region: Kerry, Clare
Meaning: Derived from Ó Gríobhtha, meaning “descendant of the griffin-like one,” the name has an association with mythical strength and leadership. The Griffins were a Dalcassian family who served as warriors under Brian Boru. Over time, they became known as chieftains in parts of Kerry and Clare, with some later rising to prominence in literature and politics. Today, the name is widespread in Ireland and among Irish-American communities.

🏹 Gaughan (Ó Gaibhtheacháin)

Pronunciation: GAW-han
First recorded: 13th century
Region: Mayo
Meaning: This name shares its origins with Gavaghan, meaning “descendant of the fierce warrior.” The Gaughans were an important sept in County Mayo, traditionally linked to the ruling O’Dowds. Some members became renowned archers, which is reflected in their frequent military roles throughout Irish history. The name is still common in Connacht, particularly in Mayo.

🔥 Gildea (Mac Giolla Dhé)

Pronunciation: gil-DAY
First recorded: 14th century
Region: Donegal
Meaning: Meaning “son of the servant of God,” Gildea is a deeply religious last name, indicating historical ties to monastic orders. The name is associated with Donegal, where the Gildeas were often scholars or clergy members in Gaelic Ireland. Some family members held influential positions in Irish Catholic movements, particularly in the 19th century. Today, it is still a common last name in Ulster.

🏰 Gilfoyle (Mac Giolla Phoil)

Pronunciation: gil-FOIL
First recorded: 15th century
Region: Kilkenny
Meaning: Mac Giolla Phoil means “son of the servant of St. Paul,” highlighting early religious connections. The Gilfoyles were a prominent family in medieval Kilkenny, often serving as scribes and historians for local chieftains. Some later transitioned into landowning roles, though many lost their lands following the Cromwellian confiscations. The name remains concentrated in Leinster today.

⚒️ Gillen (Mac Gilleáin)

Pronunciation: GILL-en
First recorded: 12th century
Region: Antrim
Meaning: Mac Gilleáin means “son of the servant of St. John,” indicating a religious dedication. The Gillens were historically linked to the O’Neills of Ulster, often acting as blacksmiths or armorers. They played an important role in maintaining weapons for Irish clans resisting English incursions. The name is still prevalent in Antrim, with some emigrants establishing strong roots in Scotland and North America.

🌊 Gormley (Ó Gormghaile)

Pronunciation: GORM-lee
First recorded: 11th century
Region: Tyrone, Derry
Meaning: Ó Gormghaile translates to “descendant of the blue valor,” combining gorm (blue) and gal (valor or bravery). This name suggests a connection to warriors or seafarers, as blue often symbolized the ocean. The Gormleys were historically associated with the O’Neills of Tyrone, serving as military leaders and advisors. The name remains common in Ulster, with some variations appearing in Scotland due to migration during the medieval period.

🔥 Gilroy (Mac Giolla Rua)

Pronunciation: GIL-roy
First recorded: 13th century
Region: Fermanagh, Donegal
Meaning: Mac Giolla Rua means “son of the red-haired servant,” indicating a lineage with distinct red hair or devotion to a leader with red hair. The Gilroys were known as warriors and horsemen, often serving as cavalry in Gaelic armies. Historically, they were vassals of the Maguires of Fermanagh. Over time, many Gilroys emigrated to Scotland, where the name evolved into MacIlroy in some areas.

⚒️ Gibney (Mac Giobúin)

Pronunciation: GIB-nee
First recorded: 14th century
Region: Meath, Westmeath
Meaning: Derived from Mac Giobúin, meaning “son of the smith,” this last name highlights a family tradition of blacksmithing. The Gibneys were highly skilled metalworkers in medieval Ireland, forging weapons and tools for local chieftains. Their trade granted them significant influence, particularly under the ruling O’Melaghlins of Meath. In later centuries, some Gibneys became prominent merchants and business owners. The name is still found across Leinster today.

Last Names with a Strong Irish Influence

🏹 Garrity (Ó Gairbheith)

Pronunciation: GAR-i-tee
First recorded: 12th century
Region: Donegal
Meaning: Ó Gairbheith translates to “descendant of the rough or fierce one,” likely referring to an ancestor known for their strength or battle prowess. The Garrity family was historically associated with the northern Ui Neill and played a key role in defending Donegal against both Viking and Norman incursions. While the name has since spread, it remains most common in Ulster and among Irish-American descendants.

🏴‍☠️ Graham (Mac Grahám)

Pronunciation: GRAY-um
First recorded: 12th century
Region: Ulster, originally Scottish
Meaning: Of Scottish origin, the Graham last name is linked to the Anglo-Norman de Graham family. It was brought to Ulster in the 1600s during the Plantation of Ireland. Many Grahams settled in Fermanagh and Antrim, becoming part of the Scots-Irish community. The name itself may derive from the Old English grāham, meaning “gravelly homestead.” Famous bearers include Alexander Graham Bell, the inventor of the telephone, whose ancestors were Scottish but had Irish links.

🍀 Grady (Ó Gráda)

Pronunciation: GRAY-dee
First recorded: 13th century
Region: Clare, Limerick
Meaning: Ó Gráda means “descendant of Gráda,” which is believed to mean “noble” or “illustrious.” The Gradys were a powerful Dalcassian family closely tied to the O’Briens, ruling parts of Clare and Limerick. They were known as historians and poets, often recording Irish history in manuscripts. Over time, the name became widespread, particularly in the U.S. due to Irish emigration.

⚓ Gilman (Mac Giolla Mháille)

Pronunciation: GILL-man
First recorded: 14th century
Region: Mayo
Meaning: Mac Giolla Mháille translates to “son of the servant of Mary.” This name is closely related to the powerful O’Malley clan of Mayo, who were renowned as seafarers and pirates, including the famous Grace O’Malley (Gráinne Mhaol). The Gilmans were often traders and shipbuilders along the western coast. Though less common today, the name retains its strong historical ties to the sea.

🔵 Gorman (Ó Gormáin)

Pronunciation: GOR-man
First recorded: 10th century
Region: Meath, Westmeath
Meaning: Ó Gormáin means “descendant of the blue one,” referring to someone who wore blue clothing or had a connection to water. The Gormans were an ancient family from the midlands, often serving as brehons (judges) in Gaelic society. They played a role in early Irish legal traditions and later became prominent landowners. The name spread globally due to Irish emigration, particularly to America and Australia.

⚖️ Gilsenan (Mac Giolla tSeanaigh)

Pronunciation: GILL-se-nan
First recorded: 16th century
Region: Meath, Cavan
Meaning: Meaning “son of the servant of St. Senan,” this last name is linked to devotion to the 6th-century Irish saint. The Gilsenans were historically associated with County Meath and were known as legal scholars and advisors to Gaelic lords. While less common than some other last names, it remains a notable name in parts of Ireland and among Irish emigrants.

🏇 Gavan (Ó Gábháin)

Pronunciation: GAV-an
First recorded: 14th century
Region: Louth, Monaghan
Meaning: Derived from Ó Gábháin, meaning “descendant of the horseman” or “descendant of the blacksmith,” the name suggests a lineage of warriors or craftsmen. The Gavans were originally associated with Louth and Monaghan, often serving as cavalry for Gaelic chieftains. Many later emigrated to the U.S., where the name took on variations like Gavin.

🌿 Greenan (Ó Gríogháin)

Pronunciation: GREEN-an
First recorded: 12th century
Region: Tyrone, Monaghan
Meaning: Ó Gríogháin likely derives from Gríoghan, a diminutive of Gregory, meaning “watchful” or “vigilant.” The Greenans were historically connected to the O’Neills of Tyrone, often serving as advisors and land stewards. Though the name is less common today, it retains a strong presence in northern and midland counties.

🏹 Gilligan (Ó Giollagáin)

Pronunciation: GILL-i-gan
First recorded: 13th century
Region: Mayo, Roscommon
Meaning: Ó Giollagáin means “descendant of the young servant” or “follower of a youth.” This name likely originated from a family with historical ties to fostering or serving noble households. The Gilligans were most commonly found in Connacht and played roles as land stewards and minor chieftains. Over time, emigration spread the name widely, with strong concentrations in the United States and Australia today.

🦁 Grogan (Ó Gruagáin)

Pronunciation: GROH-gan
First recorded: 11th century
Region: Offaly, Westmeath
Meaning: Ó Gruagáin is derived from gruaig, meaning “hair” or “mane,” possibly referencing a family known for their distinctive appearance. The Grogans were originally warriors in Leinster, serving under the O’Melaghlins and later the O’Connors. The name gained prominence in the 17th century when members of the family became influential landowners, but many were dispossessed during Cromwellian times. Today, it remains a strong last name in the Midlands.

⚒️ Gossan (Ó Gosan)

Pronunciation: GOSS-an
First recorded: 14th century
Region: Waterford, Wexford
Meaning: The last name Ó Gosan is believed to derive from an old Gaelic word related to blacksmithing or craftsmanship. Historically, the Gossans were skilled metalworkers and armorers, particularly in the southeast of Ireland. The name is relatively rare today but still found in pockets of Waterford and Wexford, with some variations appearing in England and North America.

⛪ Gillespie (Mac Giolla Easpaig)

Pronunciation: gil-ES-pee
First recorded: 12th century
Region: Donegal, Tyrone (also Scotland)
Meaning: Mac Giolla Easpaig means “son of the servant of the bishop,” reflecting a religious connection. This name has both Irish and Scottish roots, with branches of the family appearing in Ulster and the Scottish Highlands. The Gillespies were historically scribes, priests, and advisors to Gaelic lords, particularly the O’Donnells of Donegal. Many later served in the British military, and the name is now widespread across the English-speaking world.

🏰 Gillett (Mac Giolla Íde)

Pronunciation: GILL-it
First recorded: 15th century
Region: Limerick, Cork
Meaning: Mac Giolla Íde translates to “son of the servant of St. Íde,” referring to a strong devotion to St. Íde, a revered early Irish saint. The Gilletts were a minor sept in Munster, closely tied to the ruling Gaelic families. Over time, the name took on an Anglo-Norman influence, with some branches becoming traders and merchants. Today, the name is more common in England, though it retains Irish roots.

🦅 Griffey (Ó Gríofa)

Pronunciation: GRIF-fee
First recorded: 13th century
Region: Clare, Limerick
Meaning: Ó Gríofa means “descendant of the griffin-like one,” likely referencing a strong or noble ancestor. The Griffeys were an offshoot of the larger Griffin family, a Dalcassian clan connected to Brian Boru. They held land in Clare and Limerick, with many members becoming scholars and poets. The name has endured, particularly in Clare, where it remains common today.

🌊 Gaughran (Ó Gachráin)

Pronunciation: GAW-hran
First recorded: 16th century
Region: Meath, Louth
Meaning: Ó Gachráin is believed to mean “descendant of the rough or turbulent one,” suggesting a warrior lineage. The Gaughrans were known for their resistance to English rule and were involved in several uprisings in the 17th century. They were particularly associated with the ancient kingdom of Brega (modern Meath and Louth). Today, the name is less common but still found in the Irish midlands and among Irish-American families.

Get lost in the beauty of Irish names with our extensive collections of first and last names, organized by theme, meaning, and history to help you find the perfect one.