Fergus mac Léti

His place in the traditional chronology is not certain – according to some sources, he was a contemporary of the High King Conn of the Hundred Battles,[1] in others of Lugaid Luaigne, Congal Cláiringnech, Dui Dallta Dedad and Fachtna Fáthach.

In the reign of Fachtna Fáthach, Ross was killed in the Battle of Lough Foyle, and Fergus was made king of Ulster again.

In the Saga of Fergus mac Léti, he encounters water-sprites called lúchorpáin or "little bodies"; this is thought to be the earliest known references to leprechauns.

Fergus returns to Loch Rudraige in search of the sea-monster, and after a two-day battle that turns the sea red with blood, kills it, before dying of exhaustion.

Similarly to the lúchorpáin of Fergus mac Leti's legend, however, the leprechauns in the movie are seen specifically granting three wishes when caught.

"Fergus goes down into the lake", illustration by Stephen Reid in T. W. Rolleston 's The High Deeds of Finn (1910)