Hugh Annesley, 5th Earl Annesley DL (26 January 1831 – 15 December 1908) was a British military officer and Member of Parliament for County Cavan from 1857 to 1874.
He became a professional soldier and served in the Kaffir Wars in South Africa, 1851 to 1853 in the 43rd Light Infantry. He was wounded in this war, and in the Crimean War his jaw was shattered by a bullet at the Battle of the Alma in 1854. He retired as a Colonel of the Scots Fusilier Guards in 1860. He was elected conservative MP for Cavan in 1857, holding the seat until 1874. This was a family seat, and Annesley was a reluctant politician, speaking rarely in the commons and only on army matters. He retired from politics when Cavan became a centre of support for Home Rule. Six months later, his brother William Richard Annesley, 4th Earl Annesley, died unmarried, and Hugh succeeded as 5th Earl Annesley and to the family seat of Castlewellan Castle. In 1877, he was elected as a Representative Peer, serving until his death.
Annesley had a keen interest in horticulture and established an arboretum at Castlewellan. He was assisted in this by his head gardener, Thomas Ryan. He oversaw the creation of the Donard nursery company in Newcastle, County Down. He was a pioneering amateur photographer. At the request of the Royal Agricultural Society he published a book, Beautiful and rare trees and shrubs (1903), illustrated with his own photographs.
Annesley died on 15 December 1908 at Castlewellan. An obituary appeared in The Times which stated that Annesley had one of the largest collections of exotic shrubs and trees in the United Kingdom. The earldom and Castlewellan estate passed to his son Francis.
Thirty-five albums of his photographs are in the Public Record Office of Northern Ireland. They include pictures taken during the wars in South Africa and the Crimea, and during a visit to Japan, as well as photographs of his home at Castlewellan and the surrounding area.