Oliver FitzWilliam, 1st Earl of Tyrconnell (died 11 April 1667) was an Irish nobleman.

His father was Thomas FitzWilliam, 1st Viscount FitzWilliam, who was born in 1581 and died 1665.

He was both a Catholic

Catholic

The word catholic comes from the Greek phrase , meaning "on the whole," "according to the whole" or "in general", and is a combination of the Greek words meaning "about" and meaning "whole"...

 and a royalist

Cavalier

Cavalier was the name used by Parliamentarians for a Royalist supporter of King Charles I and son Charles II during the English Civil War, the Interregnum, and the Restoration...

. In 1645 he tried to get the Confederation of Kilkenny to support King Charles I

Charles I of England

Charles I was King of England, King of Scotland, and King of Ireland from 27 March 1625 until his execution in 1649. Charles engaged in a struggle for power with the Parliament of England, attempting to obtain royal revenue whilst Parliament sought to curb his Royal prerogative which Charles...

 in the English Civil War

English Civil War

The English Civil War was a series of armed conflicts and political machinations between Parliamentarians and Royalists...

 on the grounds that their Catholic demands would be met. He fought with the Confederates against the Parliamentarians in 1645–6, and led a successful assault on Roscommon Castle in 1646.

He died at Merrion Castle, 11 April 1667, and was buried on 12 April 1667 in Fitzwilliam Chapel, Donnybrook

Donnybrook, Dublin

Donnybrook is a district of Dublin, Ireland. It is situated on the southside of the city, in the Dublin 4 postal district, and is home to the Irish state broadcaster RTÉ. It was once part of the Pembroke Township...

 church.

Family

1st marriage to Dorothy Brereton,
2nd marriage to Lady Eleanor Holles, daughter of John Holles, 1st Earl of Clare

John Holles, 1st Earl of Clare

John Holles, 1st Earl of Clare was an English nobleman.He was the son of Denzel Holles of Irby upon Humber and Eleanor Sheffield...