John Andrew Hamilton, 1st Viscount Sumner, (3 February 1859 – 24 May 1934) was a British lawyer and judge.
He was appointed a judge of the High Court of Justice (King's Bench Division) in 1909, a Lord Justice of Appeal in 1912 and a Lord of Appeal in Ordinary (Law Lord) in 1913.
Created a life peer as Baron Sumner in 1913, he was further honoured when he was granted a hereditary peerage as Viscount Sumner in 1927.