About the O'Brien surname
The surname O'Brien is associated with a patronymic formation. The O' particle is an old Irish patronymic formation associated with descent. The surname may originally have expressed descent before becoming fixed as a hereditary family name. The O’ particle in O'Brien is characteristic of many Irish surnames and traditionally refers to descent. In the normalization used for some LAFRANCE searches, the surname is also matched through the form “obrien”; this search variant can be useful when accents, spaces, or punctuation differ.
Pronunciation:
Eou-bra-jeurn/əʊbʁajœʁn/