Most of the information on the gods of Ireland and Wales is from various myths, so details can vary depending on the source; particularly in the case of Wales, mythological characters are not always identified as deities, possibly due to the stories having been written down in the post-Christian era. I am taking the broad view here and using the words “goddess” and “god” to refer to these supernatural entities.

Most of the information on the gods of Britain and Gaul, on the other hand, is archaeological or historical, a circumstance that provides its own challenges including the tendency of the Roman writers to equate all gods with their own. As a polytheist, I see each deity as unique, something I hope comes through in this book; it’s not a matter of theology, it’s a matter of practicality and what seems to work.

The Celtic gods did not comprise a pantheon in the sense that the Greek or Roman gods did–most of these deities were associated with specific tribes and/or regions, and would not have been worshipped together traditionally unless they both came from the same region, and possibly not then.

Also please note that these descriptions are intentionally very brief and minimal; I’ve listed names, locations and some possible associations, but these are necessarily incomplete.  A god I’ve listed as “associated with warfare,” for example, was certainly far more than that to their people.

Abandinus
Britain. (Worship site near Godmanchester.) God. Possibly a protective deity, possibly associated with a river or spring.

Abelio
Gaul. (Worship sites along the Garonne in southwest France.) God. May be associated with the apple tree.

Abnoba
Gaul and Britain. Goddess. Associated with the hunt and the wilderness.

Aengus
Ireland. God. Tuatha de Danann. Also known as Oengus, Aengus Og or Aengus mac Og. Associated with love and inspiration.

Aine
Ireland. Goddess. Tuatha de Danann. Associated with midsummer and sovereignty.

Airmed
Ireland. Goddess. Tuatha de Danann. Associated with herbs and healing.

Alaisiagae
Britain (Worship site at Housesteads Fort near Hadrian’s Wall.) Goddesses. Associations uncertain. Beda and Boudihillia are possibly Celtic names while Fimmilena and Friagabis are more likely Germanic.

Alateivia
Gaul. (Worship site at Xanten.) Goddess. Possibly associated with healing.

Alaunus
Gaul (Worship sites in modern-day Austria.) God. Associated with healers and seers.

Alisanos
Gaul (Worship sites in modern-day France.) God. Possibly associated with stone, or the earth.

Amaethon
Wales. God.  Likely associated with agriculture.

Ambisagrus
Gaul. (Worship site at Aquileia in Italy.) God. Possibly a tribal deity.

Ancamna
Gaul. (Worship sites at Trier and Mohn, Germany.) Goddess. Possibly associated with healing springs or rivers.

Ancasta
Britain. (Worship site near Southampton.) Goddess. Possibly associated with the River Itchen.

Andraste
Britain. (Worship sites near Norfolk.) Goddess. Known as a goddess of Boudica’s Iceni tribe. Associated with warfare.

Arawn
Wales. God. Lord of the dead; associated with fertility.

Arduinna
Gaul. (Worship sites in the Ardennes.) Goddess. Associated with the wilderness; images show her riding a boar.

Arianhrod
Wales. Goddess. Mother of Dylan and Lleu.

Artio
Gaul. (Worship sites near Bern, Switzerland and in parts of western Germany.)Goddess. Associated with the bear.

Arvolecia
Britain. (Worship site near Brough, Yorkshire, England.) Goddess. Possibly associated with healing.

Aueha
Gaul. (Worship sites near Hurth, Germany.) Goddess. Possibly associated with a river or spring.

Aveta
Gaul. (Worship sites near Trier, Germany.) Goddess. Associated with motherhood.

Baduhenna
Gaul and Germania. (Worship sites in Frisia.) Goddess. Likely a battle-goddess, perhaps a tribal protector.

Be Binn
Ireland. Goddess. Tuatha de Danann. Associated with childbirth and the afterlife.

Belatucadros
Britain. (Worship sites in northern England.) God. Associated with battle.

Belenos
Gaul and Britain. (Worship sites across Europe.) God. Associated with the sun and with healing.

Beli Mawr
Wales. Goddess. Father of the gods and perhaps the tribe, possibly associated with the land of the dead.

Belisama
Gaul and Britain. (Worship sites in Gaul and northern England.) Goddess. Associated with rivers and lakes; possibly associated with the sun and summer.

Bergusia
Gaul. (Worship site in Alesia.) Goddess. Associated with abundance and/or metalwork. Consort of Ucuetis.

Bibracte
Gaul. (Worship site in what is now Autun in Burgundy, France.) Goddess. Eponymous goddess of a great Gaulish city.

Blodeuwedd
Wales. Goddess. Bride of Lleu Llaw Gyffes, created from flowers.

Boann
Ireland. Goddess. Tuatha de Danann. Mother of Aengus by the Dagda. Associated with the Boyne River.

Borvo
Gaul (Worship sites primarily in northeastern France but spread elsewhere as well.) God. A consort of Damona. Associated with healing.

Braciaca
Britain. (Worship site near Derby, England.) Goddess. Possibly a patron of brewers. Some believe this deity to be male.

Bran
Wales. God. Son of Llyr. Associated with leadership.

Branwen
Wales. Goddess. Daughter of Llyr.

Bricta
Gaul and Britain. (Worship sites at Luxeuil, France and Blackmoorgate, England.) Goddess. Associated with healing.

Brigantia
Britain. Goddess. A tribal deity; associated with healing and rivers.

Brigid
Ireland. Goddess. Tuatha de Danann. Also known as Brigit, Bride or Brid. Daughter of the Dagda. Associated with poetry, healing and crafts, particularly smithing.

Britovius
Gaul. (Worship site at Nimes, France.) God. Possibly a protective or warrior deity.

Camulus
Gaul and Britain. (Many worship sites throughout Gaul.) God. Associated with war and battle.

Carantana
Gaul. (Worship site at Etrechy, France.) Goddess. Possibly associated with wisdom; name refers to constancy.

Catubodua
Gaul. (Worship site in Haute-Savoie, France.) Goddess. Possibly associated with battle.

Caturix
Gaul (Worship sites in the Swiss Alps.) God. Likely a battle god and tribal protector.

Cernunnos
Gaul. (Worship sites near Paris, France and likely a deity with widespread worship across the region.). God. Associated with nature and commerce.

Cerridwen
Wales. Goddess. Sorceress. Associated with poetry, inspiration and transformation. First attested in the Tale of Taliesin, which may date to the 9th–12th century.

Cliodhna
Ireland. Goddess. Tuatha de Danann. Associated with beauty and love; also associated with the banshee.

Cobba
Gaul. (Worship site near Utrecht in the Netherlands.) Goddess. Associations uncertain.

Cocidius
Britain. (Worship sites near Hadrian’s Wall.) God. Associated with battle and hunting.

Condatis
Britain and Gaul (Worship sites in Brittany and Yorkshire.) God. Battle god; associated with confluences of waterways.

Coventina
Britain. (Worship sites near Northumberland.) Goddess. Associated with fresh-water springs and wells.

Creidhne
Ireland. God. Tuatha de Danann. Associated with crafts, specifically goldsmithing. One of the three gods of art, with Luchtaine and Goibniu.

Cuda
Britain. (Worship site at Cirencester in the Cotswolds.) Goddess. Associated with prosperity and good health.

Dagda
Ireland. God. Tuatha de Danann. Father of many gods. Associated with power and plenty, holder of a magical club and a bottomless cauldron.

Damona
Gaul. (Worship sites in eastern France.) Goddess. Sometimes paired with Borvo. Associated with healing springs and spas.

Danu
Ireland. Goddess. Mother of the Tuatha de Danann (People of Danu). Associated with the land.

Dian Cecht
Ireland. God. Tuatha de Danann. Associated with healing.

Donn
Ireland. God. Associated with the dead; considered an ancestor of the Irish people.

Eithne
Ireland. Goddess. Daughter of the Fomorian king Balor. Mother of Lugh.

Entarabus
Gaul. (Worship sites in Belgium, Luxembourg, Germany and France.) God. Possibly a protective god.

Epona
Gaul, Germania and Britain. (Worship sites all over Europe, including Rome.) Goddess.  Associated with horses (and cavalry), fertility and abundance.

Erecura
Gaul. (Many worship sites in the Danube region.) Goddess. Associated with fertility and the underworld.

Esus
Gaul. (Worship sites in Paris, France and Trier, Germany.) Connected with Taranis and Teutates.

Etain
Ireland. Goddess. Tuatha de Danann. Best known for her role in “The Wooing of Etain.” Subject to many transformations.

Etiona
Gaul. (Worship site at Etrechy, France.) Goddess. Possibly associated with knowledge.

Fand
Ireland. Goddess. Tuatha de Danann. Associated with the sea and with the faeries.

Fionnghula
Ireland. Goddess. Tuatha de Danann. Daughter of Lir; swan-maiden.

Flidais
Ireland. Goddess. Tuatha de Danann. Associated with shapeshifting, cattle and plenty.

Gamaleda
Gaul. (Worship site at Maastricht in the Netherlands.) Goddess. Possibly associated with age and wisdom.

Garmangabis
Britain. (Worship site near Durham, England.) Goddess. Possibly a goddess of abundance.

Glanis
Gaul. (Worship site at the ancient city of Glanum in modern Provence, France.) God. Associated with a healing spring.

Gnatus
Gaul. (Worship site at Etrechy, France.) God. Possibly associated with knowledge.

Gobannus
Gaul. (Worship site near Bern, Switzerland.) God. Likely a god of smiths.

Goibniu
Ireland. God. Tuatha de Danann. Associated with crafts, specifically smithing. One of the three gods of art, with Creidhne and Luchtaine.

Gofannon
Wales. God. Associated with smithing.

Grannus
Gaul and Germania. (Worship sites in northern Germany and France.) God. Associated with healing springs; in some places associated with the sun.

Gwydion
Wales. God. Brother of Arianhrod, uncle of Lleu. Associated with magic.

Haeva
Gaul and Germania. (Worship site in the Netherlands.) Goddesses. Likely a protector of family and children.

Hariasa
Gaul and Germania. (Worship site in Cologne, Germany.) Goddess. Possibly a goddess of war.

Harimella
Britain. (Worship site at Birrens near Hadrian’s Wall.) Goddess. Likely associated with battle; may have been associated with gatherings such as the Thing.

Hellivesa
Gaul. (Worship site near Hurth, Germany.) Goddess. Possibly associated with the river Elle.

Hidua
Gaul. (Worship site at Etrechy, France.) Goddess. Possibly associated with childbirth.

Hludana
Gaul and Germania. (Worship sites in the Netherlands and northern Germany.) Goddess. Possibly associated with the earth.

Icauna
Gaul. (Worship site at Auxerre, France.) Goddess. Likely associated with the Yonne River.

Icovellauna
Gaul. (Worship site in Metz and Trier in Germany.) Goddess. Likely associated with a healing spring.

Isosa
Gaul. (Worship site at Etrechy, France.) Goddess. Name means “respected one.”

Latis
Britain. (Worship Site in Cumbria near Hadrian’s Wall.) Goddess. Possibly associated with water and with strong drink.

Lenus
Gaul and Britain. (Worship sites in Trier and Pommern, Germany and in Caerwent and Chedworth, England.) God. A healing god, likely also a protector of the tribe.

Leucetius
Gaul. God. Consort of Nematona.

Lir
Ireland. God. Tuatha de Danann. Associated with the sea.

Litavis
Gaul. (Worship sites in Brittany.) Goddess. Perhaps a mother goddess.

Lleu
Wales. God. Called “Lleu Llaw Gyffes.” Son of Arianhrod. Associated with battle and magic.

Llyr
Wales. God. Possibly associated with the sea. Likely cognate with Ireland’s Lir.

Luchtaine
Ireland. God. Tuatha de Danann. Associated with crafts, specifically woodworking. One of the three gods of art, with Goibniu and Creidhne.

Lugh
Ireland. God. Tuatha de Danann. Called “Lugh Lamhfada” (Lugh of the Long Arm). Master of all art and craft. Associated with excellence and skill.

Lugus
Gaul. (Worship sites in France including Montmarte; other sites include Galicia in Spain.)  God.  Associated with animals, and with money.

Mabon
Wales. God. Called Mabon ap Modron. Associated with hunting.

Magla
Gaul. (Worship site at Sisek, Croatia.) Goddess. Associated with leadership, hunting.

Manannan
Ireland, Isle of Man. God. Tuatha de Danann Called “Manannan mac Lir” (Manannan son of Lir). Associated with the sea and the afterlife.

Manawyddan
Wales. God. Associated with various tales and skills, likely related to the Irish Manannan.

Maponus
Gaul and Britain. (Worship sites at Bourbonne-les-Bains in France, and at Ribchester, Corbridge and Chesterholm in Britain.) God. Likely associated with youth. May be linked to the Welsh Mabon ap Modron.

The Matrones
Gaul and Germania. (Worship sites in northwestern Europe.) Goddess. Triad of goddesses associated with family and fertility.

Medb
Ireland. Goddess. Associated with kingship and intoxication.

Meduna
Gaul. (Worship site near Trier, Germany.) Goddess. Associated with mead, likely associated with kingship.

Melusine
Gaul. Goddess. Associated with fresh-water sources such as rivers and springs. Featured in numerous medieval tales.

Moccus
Gaul. (Worship site at Langres, France.) God. Possibly associated with boar hunting.

Modron
Wales. Goddess. Mother of Mabon. Likely associated with motherhood and fertility.

Mogons
Britain and Gaul. Associations uncertain, had Gallic and Roman devotees.

Moritasgus
Gaul. (Worship sites in Burgundy, France.) God. Likely a healing deity.

Morrigan
Ireland. Goddess. Tuatha de Danann. Associated with war and kingship.

Mullo
Gaul. (Worship sites in Brittany and Normandy.) God. Associated with healing, particularly of the eyes.

Nantosuelta
Gaul. (Worship sites in the Alsace-Lorraine region.) Goddess. Associated with fertility and prosperity.

Naria
Gaul. (Worship sites in Switzerland.) Goddess. Probably associated with fertility and, perhaps, good fortune.

Nehellenia
Gaul and Germania. (Worship sites in Zeeland in the Netherlands.) Goddess. Uncertain whether her origins are Celtic or Germanic. Associated with sea travel and trade.

Nematona
Gaul and Britain. (Worship sites in Bath, England and Trier, Germany, among others.) Goddess. Tribal deity of the Nemetes; may be associated with sacred places.

Nemausus
Gaul. (Worship sites around Nimes, France.) God. Associated with a healing spring, god of the city.

Nimue
Wales. Goddess. Associated with lakes and springs.

Nodens
Britain and possibly Gaul. (Worship sites in Gloustershire, Englahd and perhaps Mainz, Germany.) God. Possibly associated with the sea and with hunting.

Noreia
Gaul. (Worship sites in northern Gaul including what is now the Austrian Alps.) Goddess. Likely a protective deity.

Nuada
Ireland. God. Tuatha de Danann. Called “Nuada Airgetlamh” (Nuada of the Silver Arm).

Ocelus
Wales. (Worship sites in Carlisle and Caerwent.) God. Likely associated with battle and/or protection.

Ogma
Ireland. God. Tuatha de Danann. Deviser of the Ogham. Associated with eloquence and wise speech.

Ogmios
Gaul. God. Associated with eloquence and the underworld.

Olloudius
Gaul and Britain. (Worship sites range from Gloucestershire in England to southern Gaul.) God. Likely associated with multiple blessings.

Penarddun
Wales. Goddess. Wife of Llyr, mother of Manawyddan.

Rhiannon
Wales. Goddess. Associated with kingship and horses.

Ricagambeda
Britain. (Worship site at Birrens near Dumfries and Galloway, Scotland.) Possibly a battle goddess.

Ritona
Gaul. (Worship centered in what is now Trier, Germany.) Goddess. Associated with water fords.

Robur
Gaul. (Worship site at Angouleme, France.) God. Likely a god of the oak tree.

Rosmerta
Gaul. (Worship sites in a wide area including France, Germany, Belgium and the Netherlands.) Goddess. Associated with abundance.

Rudianos
Gaul. (Worship sites in France.) God. Likely a battle god.

Sandraudiga
Gaul and Germania. (Worship site at Zundert in the Netherlands.) Goddess. May be associated with prosperity, name may refer to red sands.

Satiada
Britain. (Worship site at Chesterholm.) Goddess. Possibly a protective tribal goddess.

Segomo
Gaul. (Worship sites in what is now eastern France.) God. Possibly a battle god.

Senuna
Britain. (Worship site in North Hertfordshire, discovered in 2002.) Goddess. Likely associated with a spring.

Sequana
Gaul. (Worship sites in the area of the Seine River.) Goddess. Associated with the Seine and with healing.

Setlocenia
Britain. (Worship site at Maryport, England.) Goddess. Possibly associated with the passing of time, or with great age.

Sirona
Gaul. (Worship sites in east and central Gaul and along the Danube limes.) Goddess. Sometimes consort of Grannus. Associated with healing.

Smertrios
Gaul. (Worship sites in Trier, Germany and Notre Dame, France.) God. Consort of Ancamna. Likely a provider and protector god.

Souconna
Gaul. (Worship sites around the Saone River.) Goddess. Associated with the Saone River.

Sucellus
Gaul. (Worship sites in the Alsace-Lorraine region; one site in York, England.) God. Consort of Nantosuelta. Associated with farming, brewing and winemaking.

Sulevia
Gaul and Germania. (Worship site in Trier, Germany.) Goddess. Likely concerned with domestic life.

Sulis
Britain (Worship site in Bath, England.) Goddess. Associated with healing.

Tailtiu
Ireland. Goddess. Foster mother of Lugh; the festival of Lughnasadh was created by him in her honor. Associated with agriculture. (Would also be a good deity to call on with regard to issues of fosterage.)

Tamfana
Gaul and Germania. (Worshipped between the Ruhr and the Lippe in modern Germany.) Goddess. Associations uncertain.

Taranis
Gaul and Britain. (Worship sites in Gaul and elsewhere including the Rhine region.) God. Associated with the thunderstorm. Often grouped with Teutates and Esus.

Tarvos Triganaros
Gaul. (Worship sites at Notre Dame, Paris, France and Trier, Germany.) God. Associated with a bull and three cranes, possibly associated with fertility.

Telo
Gaul. (Worship site at Perigueux, France.) God. Perhaps a hunting god, or associated with protection.

Teutates
Gaul and Britain. (Worship sites widely ranging through Gaul.) God. Associated with defense and protection. Often grouped with Esus and Taranis.

Tuireann
Ireland. God. Son of Ogma, known mainly from the tale “The Sons of Tuireann.” Possibly associated with thunder.

Ucuetis
Gaul. (Worship site in Alesia, Burgundy.) God. Associated with smithing and bronzework. Consort of Bergusia.

Verbeia
Britain. (Worship site in Ilkley in Yorkshire.) Goddess. Likely a river goddess.

Vercana
Gaul. (Worship sites at Trier and in Ernstweiler, Germany.) Goddess. Associations are unclear but may have to do with inspiration and healing.

Veteris
Britain. (Worship sites in Roman Britain, particularly Yorkshire and Durham.) God. Appears to be a god with many associations including hunting and healing.

Vihansa
Gaul. (Worship site at Tongeren, Belgium.) Goddess. Likely a battle goddess.

Visucius
Gaul. (Worship sites mainly along the Rhine.) God. Possibly associated with trade.

Vosegus
Gaul. (Worship sites in France’s Vosges region.) God. Likely a god of hunting and woodlands.

References:

Green, Miranda J. Dictionary of Celtic Myth and Legend. New York: Thames and Hudson, 1992.

Mackillop, James. Dictionary of Celtic Mythology.  New York: Oxford University Press, 1998.

Monaghan, Patricia. The Encyclopedia of Celtic Mythology and Folklore. New York: Checkmark Books, 2004.