OCeallachair

OCeallachair is a surname of Irish origin. It is an anglicized form of the Gaelic O Ceallacháin, meaning "descendant of Ceallachán." The personal name Ceallachán itself is derived from the Gaelic word "ceallach," which can have several meanings, including "bright-headed," "frequenting churches," or "troublesome."

The O'Ceallachain sept was a prominent Gaelic dynasty in the medieval period, particularly associated with the region of Munster in southwestern Ireland. They were a significant ruling family in the Kingdom of Uí Bhraic, which roughly corresponded to modern-day County Clare. Over time, as the surname spread and was anglicized, various spellings emerged, including O'Callaghan, Callaghan, and O'Kelly, though OCeallachair specifically reflects a less common or possibly archaic transliteration. Families bearing this surname are found throughout Ireland and in countries with significant Irish diaspora, such as the United States, the United Kingdom, Canada, and Australia. Genealogical research often traces the lineage of OCeallachair back to these ancient Irish roots.