Horatio Nelson, 3rd Earl Nelson (7 August 1823 – 25 February 1913) was a British politician.
He was the son of Thomas Bolton (a nephew of Horatio Nelson, 1st Viscount Nelson) by his wife Frances Elizabeth Eyre. On 28 February 1835 his father inherited the title Earl Nelson from William Nelson, 1st Earl Nelson and adopted the surname of Nelson. He died on 1 November that year, and his son Horatio succeeded to the title and the estate, Trafalgar House in Wiltshire.
He was educated at Prebendal School, Eton College & Trinity College, Cambridge, where he was president of the University Pitt Club.
In the House of Lords Lord Nelson supported the Protectionist Tories under Lord Derby, and served as party chief whip in the Lords. However, when Lord Derby formed his first government in February 1852, Nelson was replaced by Lord Colville of Culross. He never held government office.
Lord Nelson was a member of the Canterbury Association from 17 October 1850.
Lord Nelson was married on 28 July 1845 at St George Hanover Square church to Lady Mary Jane Diana Agar, daughter of the second Earl of Normanton and granddaughter of the eleventh Earl of Pembroke. She died in 1904. They had several children, including Herbert Horatio, styled Viscount Trafalgar, who died in 1905, Thomas Horatio, who succeeded his father as fourth Earl Nelson, and Edward Agar Horatio, who eventually succeeded as fifth Earl in 1947.