Daniel O'Brien was the 3rd Viscount Clare.
O'Brien was the son of Connor O'Brien, 2nd Viscount Clare and Honora O'Brien, daughter of Daniel O'Brien and Ellen FitzGerald.
Clare was appointed commander of a newly raised regiment of foot, Clare's Regiment of Foot, an Irish regiment in the Dutch Service, on 8 August 1674. He was replaced within twelve months by Sir John Fenwick. From July 1751 this regiment was known as the 5th Regiment of Foot.
Clare was captain of the Clare's Dragoons regiment which he led against William of Orange at the Battle of the Boyne and later in France. He married Philadelphia Lennard, sister of the Earl of Sussex, and together they had three children:
| Peerage of Ireland | ||
|---|---|---|
| Preceded by Connor O'Brien |
Viscount Clare 1670-1691 |
Succeeded by Daniel O'Brien |