This info was mostly taken from D.J Conway's book "Celtic Magic"
 

Angus Mac Og/ Angus of the Brugh: Ireland. One of the Tuatha De Danann. He had a gold harp that made irresistably sweet music. He had a faery palace on the on the banks of the Boyne. God of youth, love and beauty.

Anu/Dana/Dana-ana: Ireland. Mother Earth, goddess of plenty, another aspect of the Morrigu; great Goddess; greatest of all Goddesses. Sometimes she formed a trinity with Badb and Macha. Her priestesses comforted the dying and taught them. Fires were lit for her at Midsummer. She is the Maiden aspect of the triple Goddess in Ireland. Guardian of cattle and health and Goddess of fertility, comfort and prosperity.

Arawn: Wales. King of Hell; God of Annawn, the underground kingdom of the dead. God of revenge, terror, and war.

Arianrhod: Wales. Star Goddess; sky Goddess; virgin;Full Moon Goddess; goddess of reincarnation. Keeper of the circling Silver Wheel of Stars, a symbol of time or karma. Another name for this wheel is the Oar Wheel. It was a ship which carried dead people (warriors) to Emania. She was the mother of Llew Llaw Gyffes and Dylan by her brother Gwydion. Her origional consort was Nwyvre. She is the Mother aspect of the Triple Goddess in Wales. Honoured at the Full Moon. Beauty, Reincarnation and Fertility.

Badb/Badhbh: Ireland. Battle Raven; Scald-crow; the cauldron of ever producing life. War Goddess and wife of Net who was also a was God. Sister of Macha, Anu and the Morrigu. Mother aspect of the Triple Goddess in Ireland. Associated with the cauldron, ravens and crows, life, inspiration, wisdom, and enlightenment.

Banba: Ireland. Goddess; part of a triad with Fotia and Eriu. They used magick to repel invaders.

Bel/Belenus/Belenos/Belimawr: Ireland. Sun and Fire God; Great God. He is closely connected with the Druids. His name is seen in the festival of Beltane. Science, healing, hot springs, fire, success, cattle, crops, vegitation, fertility, purification.

Blodeuwedd/Blodwin/Blancheflor: Wales. Lily made of Celtic initiation ceremonies. She is also known as the ninefold Goddess of the Western Isles of Paradise. Created by Math and Gwydion as a wife for Llew, she was then changed into an owl for her adultery and plotting Llew's death. She is teh Maiden form of the Triple Goddess; her symbol is the owl; Goddess of the Earth. Flowers, lunar mysteries, wisdom, initiations.

Boann/Boannan/Boyne: Ireland.Goddess of the river Boyne; mother of Angus Mac Og by the Dagda.

Bran the Blessed/Benedigeidfran:Wales. Brother of the mighty Manawydan ap Llyr and Branwen; son of Llyr. Association with ravens. God of prophecy, the arts, leaders, the Sun, war, writing and music.

Branwen: Wales. Sister of Bran the Blessed and wife of Irish King Matholwch. Venus of the Northern Seas; daughter of Llyr; Lady of the Lake. Goddess of love and Beauty.

Brigit/Brid/Brig/Brigid: Ireland. Daughter of the Dagda; poetess. Often referred to as The Triple Brigids, Three Blessed Ladies of Britain or The Three Mothers. Another aspect of Danu; associated with Imbolc. She had an exclusive female priesthood at Kildare and an ever burning sacred fire.She had nineteen priestesses who represented the nineteen-year cycle of the Celtic Great Year. Goddess of Fire, fertility, teh hearth, all feminine arts and crafts, martial arts, healing, physicians, poetry, learning, divination, inspiration, prophecy, smithcraft, agriculture, witchcraft, occult knowledge, love.

Cernunnos/Cernowain/Cernenus/Herne the Hunter: The Horned God; God of Nature; God of the Underworld and the Astral Plane; Great Father. The Druids knew him as Hu Gadarn, the Horned God of fertility. He is portrayed sitting in the lotus position with horns on his head, curly hair, a beard and naked except for a neck torque. He was sometimes seen holding a spear and shield. His symbols were the stag, bull, ram, and horned serpent. Virility, fertility, animals, nature, reincarnation, physical love, woodlands, wealth, warriors, commerce and crossroads.

Cerridwen/Caridwen/Ceridwen: Wales. Moon Goddess; Great Mother; grain Goddess; Goddess of Nature. Wife of the giant Tegid and mother of a beautiful girl (Creiwy) and an ugly boy (Avagdu). Welsh Bards called themselves the sons of Cerridwen. The founder of their craft was said to be born of Cerridwen and to have tasted a potent brew from her cauldron of inspiration. This potion was known as greal. It was made up of six plants for inspiration and knowledge.Her symbol is a white sow. Death, fertility, inspiration, regeneration, astrology, magick, spells, poetry, herbs, science and knowledge.

Creiddylad/Creudylad/Cordelia: Wales. Daughter of the sea God Llyr. Connected with Beltain and often called the May Queen. Goddess of Summer flowers. Represents flowers and love.

The Crone: This is one aspect of the Triple Goddess. She represents death or old age, Winter, the Waning Moon, the end of things, destruction that preceeds regeneration through the cauldron of rebirth.Sacred to her are all black creatures.

The Dagda: Ireland. The Good God; All Father; Lord of the Heavens; Father of the Gods and men; Lord of Life and Death; God of magick; Earth God. He was the High King of the Tuatha De Danann. Under hollow hills in the Earth he had four great palaces. The Dagda also had several children, most important being Brigit, Angus, Midir, Ogma, and Bodb the Red. God of death and rebirth; master of all trades; Lord of perfect knowledge. He had  a cauldron called the Undry which supplied unlimited food. He also had a living oak harp which caused the seasons to change in the order they do. Protection, warriors, magick, fire, weather, prophecy, the arts, reincarnation, the harp, music, and prosperity. He is the first among magicians, warriors and artisans.

Danu/Danann/Dana: Ireland. Major Mother Goddess; ancestressof the Tuatha De Danann; Mother of the Gods; Moon Goddess; Great Mother. Another aspect of the Morrigu. Patroness of wizards, rivers, water, wells, plenty, magick, and wisdom.

Diancecht/Dian Cecht: Ireland. He once destroyed a terrible baby of the Morrigu. When he cut open the child's heart, there were three deadly serpents that could kill anything.He burned them and threw them in the river.The ashes were so deadly that the river began to boil and killed everything in it.Today the  river is called Barrow. Diancecht's children were Miach, Cian, Cethe, Cu, and Airmid. He is the God of healing, medicine, regeneration, silver working, and magick.

Don/Domnu/Donn: Ireland, Wales. Abyss; Deep Sea. Queen of the Heavens; Goddess of Sea and Air. Sometimes called a Goddess and sometimes called a God.In Ireland, Don ruled over the land of teh dead. The entrances to this Otherworld were always in the sidhe or burial mounds. Had control of the elements, eloquence.

Druantia: Queen of the Druids; Mother of the tree calendar; Fir Goddess. Knowledge, creativity, passion, trees, sexual activities, fertility and protection.

Dylan: Wales.God of the Sea; Son of the wave. Son of Arianrhod and Gwydion. His symbol was the silver fish.

Elaine: Wales, Britain. Maiden aspect of the Goddess.

Epona: Britain, Gaul. The Great Mare; Divine Horse; Goddess of horses; Mother Goddess. Crops, dogs, maternity, fertility, horse breeding, healing springs, protectress of horses and prosperity.

Eriu/Erin: Ireland. A daughter of the Dagda and one of the three queens of the Tuatha De Danann.

Flidais: Ireland. Goddess of woodlands, forests, and wild things; ruler of wild beasts. She rides in a chariot drawn by deer. She is also a shape shifter.

Goibniu/Gofannon/Govannon: Ireland, Wales. One of a triad of craftsmen. He forged all the Tuatha's weapons, these weapons were deadly and if hit with one the results were fatal. God of blacksmiths, weapon makers, fire, brewing, metal working and jewelry making.

Grear Father: The Horned God;The Lord. Lord of winter, harvest and the land of the dead. Ruler of the sky, animals, mountains, powers of destruction, regeneration and lust.

Great Mother: The Lady. Goddess of fertility, the Moon, love, flowers, Summer and water.

The Green Man: A horned deity of trees and all green things on Earth. God of the woodlands.

Gwydion: Wales. Son of Don; Druid of the mainland Gods. Wizard and Bard of North Wales. He was a shape shifter and had many different skills. His symbol was a white horse. The greatest of all the enchanters. Illusion, magick, healing, changes, the sky.

Gwynn Ap Nudd: Wales. King of the underworld and the faeries. He later became the King of the subterranean faeries.

Gwythyr: Wales. King of the upper world.

Herne the Hunter: Same as Cernunnos and teh Horned God.

The Horned God: The masculine active side of nature. Also known as Earth Father. He had sacred animals which were the bull, stag, goat and bear. God of growing things, the forest, alertness, wild animals, nature, desire, agriculture.

Llyr/Lear/Lir: Ireland, Wales. God of the sea and water.

Lugh/Luga/Llew/Lug/Lugus: Ireland, Wales. Sun God, God of war. He is celebrated at Lughnassadh. Associated with ravens, his symbol is a white stag. God of war, magick, reincarnation, lightning, journeys, manual arts, initiation, healing, socerers, poets and musicians.

Macha: Ireland. She is a war Goddess. Also the Mother of life and death. She is one of the aspects of the triple Morrigu. She is honoured at Lughnassadh.

Manannan Mac Lir/Manawydan Ap Llyr: Ireland, Wales. He is a shape shifter, chief Irish sea God. God of the sea, storms, navigators, fertility, magick, rebirth, and the arts.

Margawse: Wales. Mother aspect of the Goddess.

Math Mathonwy: Wales. God of magick, sorcery and enchantment.

Merlin/Merddin/Myrddin: Wales. Druid; Great sorcerer; Great magician. He is said to have learned all his magick from the Morgan, Viviane, Nimue and the Lady of the Lake. Master at everything he does, illusion, shape shifting, herbs, healing, prophecy, crystal reading, rituals, spells, tarot, magick, incantations, psychic abilities, divination and foreseeing.

The Morrigu/Morrigan/Morgan: Ireland, Wales. Great Queen; War Goddess. Associated with ravens and crows she is the Crone aspect fo the Goddess. She is also known as the Moon Goddess, Faery Queen, Great Mother and Great White Goddess. In her dark aspect she is the Goddess of war, death and fate. She is the patroness of Witches and priestesses. Prophecy, magick, night and revenge.

Niamh: Ireland. Helps heroes at death, a form of Badhbh.

Nuada/Nudd/Nodons/Nodens: Ireland, Wales. He who bestows wealth; The Cloud maker. Similar to Neptune, he had an unstopable sword which was one of the treasures of the Tuatha. He is the God of healing, fishing, oceans, youth, beauty, water, smiths, incantations, sailing, childbirth, and magick.

Ogma/Oghma/Ogmios/Grianainech: Ireland. Very similar to Hercules, he carries a huge club and was the champion of the Tuatha. Invented the Ogham script alphabet.God of eloquence, poets, writers, inspiration, physical strength, magick, spells, music, language, the arts and reincarnation.

Pwyll: Wales. At times he is the ruler of the underworld.

Rhiannon: Wales. Known as The Great Queen. She is the Goddess of birds and horses. Enchantments, fertility and the underworld. She is usually seen riding a swift white horse.

Scathach/Scota/Scatha/Scath: Ireland, Scotland. Underworld Goddess of the Land of Scath; Dark Goddess; Goddess in the destroyer aspect. Patroness of blacksmiths, magick, healing, martial arts and prophecy.

Taliesin: Wales. The prince of song, and a poet. Patron of the Druids, Bards and minstrels. God of magick, writing, wisdom, wizards, music, knowledge, and Bards.

Tephi: Ireland. Goddess of Tara.

White Lady: Dryad of death; identified with Macha; Queen of the Dead and Crone form of teh Goddess. Goddess of death, annihilation and destruction.