Ó Faoláin is the name of an important Irish sept prominent in the southeast of the country. The name is derived from the gaelic word "faol" meaning a wolf, "faoláin" being a diminutive form (little wolf). The original Faoláin from whom the surname is derived, was nineteenth in descent from Fiacha Suidhe, a younger brother of Conn of the Hundred Battles, who reigned as High King for thirty five years until his death in A.D. 157. This makes the O Faoláin sept of the same origin as Commisky and Ó Bric. It is said that the Irish names Ó Faoileáin and Ó hAoileáin (Hyland) are simple variant forms of the same name that arose as members of the sept spread beyond the original territory.

Many Irish names have been anglicised into a wide variety of forms and this is true of Ó Faoláin. The earliest anglicised forms were Felan and Faelan, with many similar variants. This evolved into Phelan mainly in Waterford, Kilkenny and adjacent areas and Whelan, also in these counties, but spreading into Wexford and Carlow. Whelan is the most prevalent form in modern times. It alone stands seventy-ninth in the list of the hundred commonest names in Ireland; with Phelan added the name takes forty-fourth place, with an estimated population of about twelve thousand persons. In the last year for which such statistics are available 214 births were registered for Whelan and 93 for Phelan. Eighty per cent of the latter belonged to Counties Waterford, Kilkenny and adjacent areas while Whelans extended further into Wexford and Carlow. Many, of course, were born in Dublin, but in considerations of this kind the metropolitan area can be disregarded, being populated by persons from every part of the country from early times.

It is natural that the present day representatives of the sept of Ó Faoláin should be found in the places mentioned, because their chiefs were Princes of the Decies, in west Waterford, before the arrival of the Normans.

Aryan speaks of them thus: "Two gentle chiefs whose names I tell, rule the Desies. I affirm it. O'Bric the exactor of tributes, with him the wise and fair O'Felan. In Moylacha of the fertile slopes, rules O'Felan for the benefit of his tribe. Great is the allotted territory, of which O'Felan holds possession".

By the beginning of the thirteenth century, most of their traditional lands and titles were lost to the Le Poers (Power) and other settler families in the wake of the Norman invasion.

A branch of the sept was settled a little further north in the southwest part of Co. Kilkenny, mainly in the barony of Iverk. One of these, John Phelan, was Bishop of Ossory at the time of the Catholic resurgence under James II.

The gentleman who styled himself "O'Faoláin, Prince of the Decies", a claim not allowed by the Genealogical Office, was born Whelan; the well-known writer Seán Ó Faoláin is the son of Denis Whelan. Another distinguished Whelan was Leo Whelan, R.H.A. (1892-1956), the portrait painter.

Of those using the form Phelan the best known are Edward Joseph Phelan, the Director-General of the International Labour Office, of Co. Waterford, and Frederick Ross Phelan, a distinguished Canadian soldier. In the United States, Phelans have been prominent, notably James Phelan (1824-1892), Laois-born pioneer, and his son James Duval Phelan (1861-1930), senator and mayor of San Francisco.

O'Faelan, O'Faoláin, Felan, Phelan, Whelan, Whalen (A sept in Munster derived from Faelan, chief of North Decies)

ARMS: Argent four lozenges in bend cojoined Azure between two cotises of the last, on a chief Gules three fleurs-de-lis of the first.

CREST: A stag's head Or.

MOTTO: No motto is recorded.