John Ponsonby, 4th Earl Of Bessborough

John William Ponsonby, 4th Earl of Bessborough (31 August 1781 – 16 May 1847), was a British politician associated with the Whig party. He was known as Viscount Duncannon from 1793 until 1844, when he succeeded his father as Earl of Bessborough.

He was born into the Ponsonby family, a prominent noble family from Cumberland. His father was Frederick Ponsonby, 3rd Earl of Bessborough, and his mother was Lady Henrietta Frances Spencer, daughter of John Spencer, 1st Earl Spencer. His siblings included Sir Frederick Ponsonby, William Ponsonby, 1st Baron de Mauley, and Lady Caroline Lamb. His maternal lineage involved a relationship between his mother and Lord Granville, who was her lover prior to her marriage; Lord Granville allegedly fathered two illegitimate children with her.

Ponsonby received his education at Harrow School and later attended Christ Church, Oxford. His early career in politics included serving as First Commissioner of Woods and Forests under Lord Grey from 1831 to 1834, and again under Lord Melbourne from 1835 to 1841. He was briefly appointed Home Secretary in 1834 and served as Lord Privy Seal from 1835 to 1839. In 1831, he was appointed to the Privy Council.

In 1834, ten years before inheriting the earldom, he was granted the title of Baron Duncannon, of Bessborough in the County of Kilkenny. From November 1838 until his death in 1847, he held the position of Lord Lieutenant of Kilkenny. In 1846, he was appointed Lord Lieutenant of Ireland, serving during the initial years of the Great Famine.

He was known to have a stammer, which made public speaking difficult for him. Despite this, he was regarded as a competent colleague within the government and was involved in drafting significant legislation, including the Reform Act 1832, as one of the "Committee of Four."

In addition to his political career, Ponsonby was created a Privy Counsellor in 1831 and was elevated to the peerage as Baron Duncannon in 1834. He also served as Lord Lieutenant of Kilkenny from 1838 until his death.

He married Lady Maria Fane, daughter of John Fane, 10th Earl of Westmorland, on 16 November 1805 at Berkeley Square, London. The couple had fourteen children, including their eldest son John George Brabazon Ponsonby, who became the 5th Earl of Bessborough, and other notable descendants such as Spencer Gore, Wimbledon’s first singles champion, and Charles Gore, Bishop of Oxford.

His children included:

- Lady Georgiana Sarah Ponsonby

- John George Brabazon Ponsonby, 5th Earl of Bessborough

- William Wentworth Brabazon Ponsonby

- Lady Augusta Lavinia Priscilla Ponsonby

- Frederick George Brabazon Ponsonby, 6th Earl of Bessborough

- Lady Emily Charlotte Mary Ponsonby

- Lady Maria Jane Elizabeth Ponsonby

- Hon. George Arthur Brabazon Ponsonby

- Reverend Walter William Brabazon Ponsonby, 7th Earl of Bessborough

- Rt. Hon. Sir Spencer Cecil Ponsonby-Fane

- Lady Harriet Frederica Anne Ponsonby

- Lady Kathleen Louisa Georgina Ponsonby

- Hon. Gerald Henry Brabazon Ponsonby

Lady Maria Fane died in March 1834 at the age of 46. Lord Bessborough survived her by thirteen years, passing away in May 1847 at age 65. His eldest son succeeded him as the 5th Earl of Bessborough. Bessborough Gardens in London was named in his honor.