The Dagda in the context of "Brú na Bóinne"

Lough Neagh (/lɒx ˈneɪ/ lokh NAY; Irish: Loch nEathach [l̪ˠɔx ˈn̠ʲaha(x)]) is a freshwater lake in Northern Ireland and is the largest lake on the island of Ireland and in the British Isles. It has a surface area of 148 square miles (383 square kilometres) and is about 19 miles (31 km) long and 9 miles (14 km) wide. According to Northern Ireland Water, it supplies 40.7% of Northern Ireland's drinking water.

Its main inflows are the Upper River Bann and Blackwater, and its main outflow is the Lower Bann. There are several small islands, including Ram's Island, Coney Island and Derrywarragh Island. The lake bed is owned by the 12th Earl of Shaftesbury and the lake is managed by Lough Neagh Partnership. Its name comes from Irish Loch nEachach [ˌl̪ˠɔx ˈn̠ʲahəx], meaning "Eachaidh's lake".

The Tuatha Dé Danann (Irish: [ˈt̪ˠuə(hə) dʲeː ˈd̪ˠan̪ˠən̪ˠ], usually translated "folk of the goddess Danu"), also known by the earlier name Tuath Dé ("tribe of the gods" or "divine tribe"), are a supernatural race in Irish mythology. Many of them are thought to represent deities of pre-Christian Gaelic Ireland.

The Tuath Dé Danann are often depicted as kings, queens, druids, bards, warriors, heroes, healers and craftsmen who have supernatural powers. They dwell in the Otherworld but interact with humans and the human world. They are associated with the sídhe: prominent ancient burial mounds such as Brú na Bóinne, which are entrances to Otherworld realms. Their traditional rivals are the Fomorians (Fomoire), who might represent the destructive powers of nature, and whom the Tuatha Dé Danann defeat in the Battle of Mag Tuired. Prominent members include the Dagda ("the great god"); The Morrígan ("the great queen" or "phantom queen"); Lugh; Nuada; Aengus; Brigid; Manannán; Dian Cecht the healer; and Goibniu the smith, one of the Trí Dé Dána ("three gods of craft"). Several of the Tuath Dé are cognate with ancient Celtic deities: Lugh with Lugus, Brigit with Brigantia, Nuada with Nodons, Ogma with Ogmios, and Goibniu with Gobannus.

In Irish mythology, Aengus or Óengus is one of the Tuatha Dé Danann and probably originally a god associated with youth, love, summer and poetic inspiration. The son of The Dagda and Boann, Aengus is also known as Macan Óc ("the young boy" or "young son"), and corresponds to the Welsh mythical figure Mabon and the Celtic god Maponos. He plays a central role in five Irish myths.

Brigid or Brigit (/ˈbrɪdʒɪd, ˈbriːɪd/ BRIJ-id, BREE-id, Irish: [ˈbʲɾʲiːdʲ]; meaning 'exalted one'), also Bríd, is a goddess of pre-Christian Ireland. She appears in Irish mythology as a member of the Tuatha Dé Danann, the daughter of the Dagda and wife of Bres, with whom she had a son named Ruadán. Her sacred tree appears to have been the birch, given some older Imbolc-related traditions.

She is associated with wisdom, poetry, healing, protection, smithing and domesticated animals. Cormac's Glossary, written in the 9th century by Christian monks, says that Brigid was "the goddess whom poets adored" and that she had two sisters: Brigid the healer and Brigid the smith. This suggests she may have been a triple deity. She is also thought to have some relation to the British Celtic goddess Brigantia.