Celtic onomastics


is an important source of information on the early Celts, as Greco-Roman historiography recorded Celtic names before substantial written information becomes available in any Celtic language.
Like Germanic names, early Celtic names are often.

Suffixes

Some information on prehistoric Celtic polytheism can be drawn from names in Irish and Welsh mythology, which often continue older theonyms:
Many surnames of Gaelic origin in Ireland and the other Celtic nations, derive from ancestors' names, nicknames, or descriptive names. In the first group can be placed surnames such as MacMurrough and MacCarthy, derived from patronymics, or O'Brien and O'Grady, derived from ancestral names.
Gaelic surnames derived from nicknames include Ó Dubhda, O'Doherty, Garvery, Manton, Bane, Finn and Kennedy
Very few Gaelic surnames are derived from placenames or venerated people/objects. Among those that are included in this small group, several can be shown to be derivations of Gaelic personal names or surnames. One notable exception is Ó Cuilleáin or O'Collins as in the Holly Tree, considered one of the most sacred objects of pre-Christian Celtic culture. Another is Walsh, meaning Welsh.
In areas where certain family names are extremely common, extra names are added that sometimes follow this archaic pattern. In Ireland, for example, where Murphy is an exceedingly common name, particular Murphy families or extended families are nicknamed, so that Denis Murphy's family were called 'The Weavers' and Denis himself was called 'Denis "The Weaver" Murphy'.
For much the same reason, nicknames, father's names or mother's maiden name can become colloquial or legal surnames. The Irish family of de Courcy descends from Anglo-Normans who came to Ireland following the Norman Conquest. The de Courcy family was prominent in County Cork from the earliest days of the Norman occupation and subsequently became prominent in Ireland.
In addition to all this, Irish-speaking areas still follow the old tradition of naming themselves after their father, grandfather, great-grandfather and so on. Examples include Mike Bartly Pat Reilly, John Michel John Oge Pat Breanach, Tom Paddy-Joe Seoige, and Mary Bartly Mike Walsh. Sometimes, the female line of the family is used, depending on how well the parent is known in the area the person resides in, e.g. Paddy Mary John. A similar tradition continues even in English-speaking areas, especially in rural districts.

Surname prefixes