Drennan
A mainly Irish surname, likely from an anglicized Gaelic personal-name form, especially associated with Ulster and the north of Ireland.
The #7,821 most common surname in the United States (2010 Census) — about 1 in every 72,938 Americans shares it.
Etymology
Drennan is generally treated as an Irish surname formed from a Gaelic personal-name source rather than from an English word. The historical spellings in Irish sources point to forms such as Drinan/Drinane/Dreinan, which are usually connected with anglicized Gaelic names beginning with O’ or Mac-style ancestry markers. The exact original Gaelic form is not entirely certain from the excerpts alone, so the safest reading is that it is a Gaelic surname that was reshaped in English spelling over time.
History
The name is recorded in Irish genealogical and surname studies in several anglicized spellings, suggesting a family-name tradition that was already well established before standard English spelling. In modern usage Drennan is found especially in Ireland and in Irish diaspora communities, with strong connections to Ulster. Variant forms in the historical record include Drinan, Drinane, and Dreinan.
Origin
Regions
Variant spellings
Fun fact
The historical sources group Drennan with several closely related Irish spellings, showing how one Gaelic family name could branch into multiple English-looking forms.
From the historical record
“0 "O^iAJriAiT), 0 "OjiAisneAin, Drinane, Drinan, Dreinan, Drennan ; Thornton. 0 *OiiAo-oA, Drudy, Droody, Draddy.”
— Sloinnte Gaedheal is Gall: Irish names and surnames