Alexander B. Moffat (1904 – 6 September 1967) was a Scottish trade unionist and communist activist who was President of the Scottish Trades Union Congress and the Scottish Mineworkers Union.
Born into a Plymouth Brethren family in Lumphinnans in Fife, Moffat left school at the age of fourteen to work at the local coal mine. His family had a long association with the trade union movement; his grandfather, David Moffat, had been the secretary of the Mid and East Lothian Miners' Association, until victimisation by employers forced him to move his family to Lumphinnans to find work. Moffat was elected as pit delegate after only four years at the mine, the youngest ever pit delegate in Scotland.
He worked with his brothers, David and Abe Moffat, in support of the national miners' strike of 1926. He was imprisoned for two months for a speech he made during the strike, and was thereafter blacklisted by local mines. He married Alice Brady, who he had met through the Young Communist League. She died during the birth of what would have been their first child, in 1928.
Thereafter, Moffat devoted much of his time to the Communist Party of Great Britain (CPGB), and in 1928 was elected to Fife County Council, replacing fellow party member Bruce Wallace. That year, he was also elected as a checkweighman, alongside his brother Abe, but the two were removed from their positions amid a dispute about their role in a dispute over payment systems. In 1928, he was also elected as Vice-President of the Fife, Kinross and Clackmannan Miners Association, and organised the Fife Miners' Gala, although the union was soon dissolved and Moffat instead became vice-president of the communist-led United Mineworkers of Scotland, and Fife organiser for the CPGB. He stood in Rutherglen at the 1929 general election, gaining 842 votes, and was not elected.