John Andrew Hamilton, 1st Viscount Sumner, GCB, PC (3 February 1859 – 24 May 1934) was a British lawyer and judge.

[5] On his appointment as Judge of the High Court of Justice (King's Bench Division) in 1909, he was knighted and invested a bencher.

[2] Already in the following year, Hamilton became a Lord of Appeal in Ordinary and created a life peer as Baron Sumner, of Ibstone, in the County of Buckingham.

[6] He was further honoured, when on 31 January 1927, he created a hereditary peerage as Viscount Sumner, of Ibstone, in the County of Buckingham.

[2] Hamilton took part at the Treaty of Versailles in 1919 as delegate of the reparations commission, for which he was appointed a Knight Grand Cross of the Order of the Bath (GCB) in the 1920 Birthday Honours.