George Hamilton Chichester, 3rd Marquess of Donegall, KP, GCH, PC (10 February 1797 – 20 October 1883) was an Irish nobleman. He was born in Great Cumberland Place, London, and was educated at Eton and Christ Church, Oxford before serving for a time as a Captain with the 11th Hussars.

In 1818 Chichester was elected to the House of Commons as Conservative Member of Parliament (MP) for Carrickfergus, and two years later became representative for Belfast. In 1830 he was finally elected Whig MP for Antrim, and was again elected to the Commons for Belfast in 1837. After unsuccessfully recontesting the seat as a Liberal candidate in 1841, he was that same year created Baron Ennishowen and Carrickfergus, of Ennishowen, County Donegal, and Carrickfergus, County Antrim. He sat in the House of Lords at Westminster for three years under this title before succeeding his father as third Marquess of Donegall in 1844.

Chichester was admitted to the Privy Council in 1830, becoming at the time of his death its senior member, and was the following year made a Knight Grand Cross of the Royal Guelphic Order. In 1841 he was appointed Lord Lieutenant of Antrim, and also later served as Captain of the Yeomen of the Guard, 1848–1852. He was finally appointed a Knight of the Order of St Patrick in 1857.

Lord Donegall died in Brighton in 1883 and was buried in Belfast. His only surviving son and heir, Frederick Richard Chichester, Earl of Belfast, having died in Naples in 1853, the larger part of the Donegall estates were inherited by the Marquess's daughter, Harriet Augusta Anna Seymourina Chichester, wife of Anthony Ashley-Cooper, 8th Earl of Shaftesbury.