Finnigan comes from an Irish surname derived from Finn, meaning fair or white.
Finnigan is an Irish surname of venerable Gaelic origin, derived from the personal name Fionnagáin — itself a diminutive of Fionn, meaning "fair," "white," or "bright." Fionn was one of the great heroic names of Celtic mythology, most famously borne by Fionn mac Cumhaill, the legendary warrior-poet and leader of the Fianna, whose exploits fill the vast Fenian Cycle of Irish literature. To carry a name rooted in Fionn is to carry a whisper of that wild, bardic Ireland.
In the English-speaking world, the name gained enormous literary gravitas through James Joyce's final masterwork, Finnegans Wake (1939), a novel so dense with wordplay and myth that the very title puns on "Finn again" — the mythic return of the hero. Joyce drew on the old Dublin ballad "Finnegan's Wake," about a hod carrier named Tim Finnegan who falls from a ladder and apparently dies, only to be revived by whiskey at his own wake. The name thus carries a sly resurrection story within it, a joke about Irish death-and-renewal that delighted Joyce.
As a given name rather than a surname, Finnigan has grown in popularity across the English-speaking world in the twenty-first century, buoyed by enthusiasm for Irish heritage names and the broader trend of converting surnames into first names. It sits alongside Finnegan and Finn as a more elaborate, characterful option — the choice for parents who want the warmth of "Finn" with a little more weight and personality attached.