The name Obrien is a boy's name of Irish origin meaning "descendant of Brian". Obrien and is often added to lists like Irish Names for Dogs and discussed in our forums with posts like "Love, Like, Lose -- Outlandish/Guilty Pleasures edition!".
From the experts:
The use of O-prefixes could create the next wave of Irish inflected names, offering an innovative way of honoring a relative with a behind the times moniker.