Ó Siadhail
Ó Siadhail / uaSiadhail / uaSiadgail is a Gaelic-Irish surname. Overview 

There were at least three families of this name in Gaelic Ireland. Ó Siadhail of Ui Maine, now east County Galway. Ó Siadhail of Uí Failghe, now County Offaly and County Laois. Ó Siadhail of Tír Chonaill, now County Donegal. Little is recorded of the Ui Maine family. Those of Uí Failghe and Tír Chonaill were ollamhs of medicine, hereditary physicians to the ruling families in the respectives kingdoms and environs. It is not clear if the two were branches of the one family, or unrelated families who happened to bear the same surname. Current forms 

The surname is now generally anglicised as O'Shiel, Shiel, Sheil, Sheils, Sheals, Sheal and Sheilds (or Shiels and Shields), but the original form, Ó Siadhail, is used by persons who are Gaelic and conscious of their genealogy. Notable bearers 
Notable people named Ó Siadhail or one of its variants include:

 Eoghan Carrach Ó Siadhail, poet, fl. c. 1500–1550
 Séamus Ó Siaghail, c. 1600 – 1655
 Michael Shiell, c. 1663 – 1700
 James Shields, 1806–1879
 Micheal O'Siadhail, poet, born 1947
 Kevin Shields, 1963 –
 Brooke Shields, 1965 –
 Jimi Shields, 1967 – 
 , 1950–2006

See also
 Shiel

References 
 Medicine and Medical Doctors, Chapter XIV, A Smaller Social History of Ancient Ireland, Patrick Weston Joyce, 1906. External links 
 http://www.irishtimes.com/ancestor/surname/index.cfm?fuseaction=Go.&UserID=
 http://www.libraryireland.com/SocialHistoryAncientIreland/II-XIV-1.php
 http://freepages.genealogy.rootsweb.ancestry.com/~grannyapple/SHIELDS%20DNA/DNA%20Test%20Results.html

Surnames
Irish families
Irish Brehon families
Surnames of Irish origin
Irish-language surnames
Families of Irish ancestry
Irish medical families