The oldest of the four cycles, telling of the Tuatha Dé Danann and the successive invasions of Ireland.
The Mythological Cycle is the earliest and most explicitly supernatural of Ireland's four narrative cycles, telling of a succession of mythical peoples who settled Ireland before recorded history, culminating in the arrival of the Tuatha Dé Danann — a divine race skilled in magic, poetry, and craft — and their wars against the monstrous Fomorians for control of the island.
Its central figures include the Dagda, Lugh, Nuada, and the Morrígan, and its events are framed by two major medieval texts: Lebor Gabála Érenn, which supplies the overall sequence of mythical invasions, and Cath Maige Tuired, which narrates the decisive battle against the Fomorians in detail. According to the tradition, after losing dominance of Ireland to the Milesians — ancestors of the Gaelic Irish — the Tuatha Dé Danann withdrew into the sídhe, the ancient burial mounds and hills, becoming the Otherworldly Aos Sí of later folklore, a transition that quietly links this oldest cycle to the fairy lore still told centuries later.
| Cycle | Entries here | Focus |
|---|---|---|
| The Mythological Cycle | 17 | The oldest of the four cycles, telling of the Tuatha Dé Danann and the successive invasions of Ireland. |
| The Fenian Cycle | 6 | Tales of Fionn mac Cumhaill and his band of warriors, the Fianna, set generations after the Ulster Cycle in a world of hunting, romance, and roaming adventure. |
| The Ulster Cycle | 12 | The heroic tales of Conchobar mac Nessa's court at Emain Macha, centered on Cú Chulainn and the great cattle raid of the Táin Bó Cúailnge. |
| The Historical Cycle | 1 | Also the Cycle of the Kings — legendary and semi-legendary tales of Ireland's High Kings, treated by medieval scribes as genuine national history. |
It's the earliest of the four cycles, telling the story of Ireland's supernatural race, the Tuatha Dé Danann, including their arrival, their wars with the Fomorians, and their eventual retreat into the Otherworld.
Lebor Gabála Érenn ("The Book of Invasions") supplies the overall framework of successive settlements of Ireland, while Cath Maige Tuired ("The Battle of Moytura") narrates the Tuatha Dé Danann's decisive wars against the Fomorians in more detail.
According to later tradition, after losing dominance of Ireland to the Milesians (ancestors of the Gaels), the Tuatha Dé Danann withdrew into the sídhe, the ancient mounds and hills, becoming the Otherworldly Aos Sí of later folklore.