Gillen
An Irish surname usually understood as a shortened form of Mac Giolla Ín or a related Gaelic name meaning “servant of John.”
The #4,188 most common surname in the United States (2010 Census) — about 1 in every 36,486 Americans shares it.
Etymology
Gillen is generally traced to an Irish Gaelic form built on giolla, meaning “servant” or “devotee,” plus a personal name element commonly taken as Ín/Íosa or a related saint’s name. In older surname collections it is grouped with forms such as MacGillen and related Gill- names, suggesting an origin in a devotional or patronymic Gaelic naming pattern. The exact underlying Gaelic form can vary by region, so the surname may reflect more than one closely related source.
History
The name is well represented in Ireland and in Irish diaspora communities, and it was recorded by 19th- and early-20th-century surname scholars as an Irish form. In some cases it is treated as a variant or shortened spelling of Killen or related Gill- surnames, reflecting the instability of anglicized Gaelic spellings. It appears in both Ireland and Scotland-linked surname lists, which fits a broader Gaelic distribution.
Origin
Regions
Variant spellings
Fun fact
Older surname dictionaries sometimes file Gillen right alongside Killen and other Gill- names because spellings could shift freely when Gaelic names were written in English.
From the historical record
“' (illam. See Gilham (illan, Gillen, Gilleny. From thelrish M'Gullian, Gillen, Killen : [gill Oin (the servant of John) (illespie. From Gillesbie ; aloe, i n., Dumfries. Or from the Gaelic Gillescop and Gillespie (the bis¬”
— British Family Names: their origin and meaning (2nd ed.)