Walter Hume Long, 1st Viscount Long (1854-1924) was a British Conservative politician of the late 19th and early 20th century. A protestant Irishman, he was a fervent Unionist. He served as President of the Board of Agriculture (1895-1900), President of the Local Government Board (1900-1905), and Chief Secretary for Ireland (1905) under Salisbury and Balfour. In 1911, he competed with Austen Chamberlain for leadership of the party, but ultimately the post went to the compromise candidate Andrew Bonar Law. In Asquith's coalition ministry of 1915, Long was again President of the Local Government Board (1915-1916), and under Lloyd George he served as Secretary of State for the Colonies (1916-1919), and First Lord of the Admiralty (1919-1921). He retired in 1921 and was raised to the peerage as Viscount Long, of Wraxall in the County of Wiltshire.

|- style="text-align: center;" | width="30%" |Preceded by:
Henry Chaplin | width="40%" style="text-align: center;" |President of the Local Government Board
1900–1905 | width="30%" |Succeeded by:
Gerald Balfour

|- style="text-align: center;" | width="30%" |Preceded by:
George Wyndham | width="40%" style="text-align: center;" |Chief Secretary for Ireland
1905 | width="30%" |Succeeded by:
James Bryce

|- style="text-align: center;" | width="30%" |Preceded by:
Herbert Samuel | width="40%" style="text-align: center;" |President of the Local Government Board
1915–1916 | width="30%" |Succeeded by:
William Hayes Fisher

|- style="text-align: center;" | width="30%" |Preceded by:
Andrew Bonar Law | width="40%" style="text-align: center;" |Colonial Secretary
1916–1919 | width="30%" |Succeeded by:
The Viscount Milner

|- style="text-align: center;" | width="30%" |Preceded by:
Sir Eric Geddes | width="40%" style="text-align: center;" |First Lord of the Admiralty
1919–1921 | width="30%" |Succeeded by:
The Lord Lee of Fareham