| John FitzPatrick, 1st Baron Castletown | |
| Office1: | Member of Parliament for Queen's County |
| Term1: | 1837–1841 1847–1852 1865–1869 |
| Party: | Liberal |
| Birth Date: | 24 September 1809 |
| Birth Place: | London, England[1] |
| Father: | John FitzPatrick |
| Children: | 7, including Bernard |
John Wilson FitzPatrick, 1st Baron Castletown PC (born John Wilson; 24 September 1809 - 22 January 1883) was an Anglo-Irish Liberal politician.
Castletown, baptised John Wilson, was born in London, the illegitimate son of John FitzPatrick, 2nd Earl of Upper Ossory and Elizabeth Wilson. He had a brother, Richard, who died young, and an elder sister, Emma Mary (died 25 September 1882), who married Robert Vernon Smith (later Lord Lyveden).[2] After their father's death in 1818, they were raised at Ampthill Park under the guardianship of their cousin Henry Vassall-Fox, 3rd Baron Holland (1773–1840), who inherited Ampthill from the earl.[3] They were also under the guardianship of their half-sisters, Lady Anne and Lady Gertrude Fitzpatrick.[4]
He inherited parts of his father's estates in Ireland in 1823, when he reached the age of majority.[3]
Wilson, who in 1842 assumed the surname of FitzPatrick by Royal Licence, was appointed High Sheriff of Queen's County in 1836. He was then elected to the House of Commons for Queen's County in 1837, a seat he represented until 1841, and again from 1847 to 1852 and from 1865 to 1869. He was admitted to the Irish Privy Council in 1848.[3]
In 1869, he was raised to the peerage as Baron Castletown, of Upper Ossory, reviving an ancient title that had belonged to the FitzPatricks around 1500.[3] Apart from his parliamentary career he was also Lord Lieutenant of Queen's County from 1855 to 1883.[6]
Lord Castletown married Augusta Mary Douglas, daughter of Reverend Archibald Douglas, in 1830. They had one son and six daughters.[6]
He died in 1883, aged 71, just four months after the death of his only sister, Lady Lyvedon.[3] Lady Castletown died in 1899.[6]
Lord Castletown was succeeded in the barony by his only son, Bernard, who died without heirs in 1937, at which time the barony became extinct.[7]