Ivor Churchill Guest, 1st Viscount Wimborne (16 January 1873 - 14 June 1939) was a British Liberal politician, and one of the last Lords Lieutenant of Ireland, serving in that position at the time of the Easter Rising.

Guest, son of the 1st Baron Wimborne, was educated at Trinity College, Cambridge, and was elected to parliament in 1900. He sat as an MP until 1910, when he was raised to the peerage as Baron Ashby St Ledgers, and became Paymaster General in the government of Herbert Henry Asquith. He served as Paymaster General until 1912, and later served as a Lord in Waiting on King George V. In 1914 he succeeded his father as Baron Wimborne, and in 1915 became Lord Lieutenant of Ireland. He served in that post for three tumultuous years. In 1918 he resigned that office, and was created Viscount Wimborne.