John Petty, 2nd Marquess of Lansdowne

The Most Honourable The Marquess of Lansdowne
2nd Marquess of Lansdowne
In office 1805–1809
Preceded by	William Petty
Succeeded by	Henry Petty-Fitzmaurice
Member of the British Parliament for Wycombe
In office 1786–1802
Personal details
Born	6 December 1765
Died	15 November 1809
Spouse	Maria Arabella Gifford Maddock
Parents	William Petty, 2nd Earl of Shelburne (father) Sophia Carteret (mother)

John Henry Petty, Earl Wycombe, 2nd Marquess of Lansdowne (6 December 1765 – 15 November 1809), was a British Whig politician who in Ireland was suspected of complicity in a republican conspiracy. In 1786, his father, the former British Prime Minister Lord Shelbourne, secured him an English seat in the House of Commons. After witnessing revolutionary events in Paris, he began to establish an independent reputation as a friend of reform, critical of the war with France and of the suppression of democratic agitation at home. In 1797 he repaired to his father's estates in Ireland where his political associations brought him under government surveillance.

After the United Irish rebellion of 1798, he was seen in the company of Robert Emmet and his confederates and was suspected by the Irish administration of being party to his plans in 1803 for a rising in Dublin. Assured of his liberty by the Irish Chief Secretary, William Wickham, who privately confessed to his own sympathy for Emmet and his cause, Petty retired in ill health to England where, in possession of his father's title Marquess of Lansdowne, he died aged 43.