Brigadier-General Sir William Alexander (4 May 1874 – 29 December 1954) was a British businessman, British Army officer, civil servant, and Scottish Unionist Party politician. He was the Member of Parliament (MP) for Glasgow Central between the general elections of 1923 to 1945, when he stood down.
Educated at Kelvinside Academy, the University of Glasgow, and Göttingen, Alexander was commissioned into the Territorial Force in 1899, becoming captain in 1906, major in 1915, and brigadier-general in 1917.
During the First World War, he commanded the 6th Battalion, The Black Watch. He was then appointed Director of Administration of Explosive Factories at the Ministry of Munitions from 1916 to 1917 and Controller of Aircraft Supply and Production at the same ministry from 1917 to 1919. He was Director-General of Purchases at the ministry from 1919 to 1920. He was a member of the Air Council in 1919.
He was a director of many companies. His chief business concerns were in chemicals and iron and steel.
He was appointed DSO in 1916, CMG in 1918, CB and TD in 1919, and KBE in 1920. He also received the Legion of Honour, and was an Officer of the Order of St Maurice and St Lazarus.