Daniel O'Brien | |
|---|---|
| Viscount Clare | |
 | |
| Tenure | 1662–1666 |
| Successor | Connor, 2nd Viscount Clare |
| Born | c. 1577 |
| Died | 1666 |
| Spouse(s) | Catherine FitzGerald |
| Issue Detail | Connor, & others |
| Father | Connor, 3rd Earl of Thomond |
| Mother | Una O'Brien-Ara |
Sir Daniel O'Brien, 1st Viscount Clare also called Donal (c. 1577 – 1666) was an Irish politician and soldier. He was born a younger son of Connor O'Brien, 3rd Earl of Thomond. He fought against the insurgents at Tyrone's Rebellion, but for the insurgents in the Irish Rebellion of 1641 and the Irish Confederate Wars. He resisted the Cromwellian conquest of Ireland. He joined Charles II of England in exile and was in his eighties made a viscount at the Restoration.