Thomas Irwin (died 1941 or 1942) was a Scottish trade unionist and politician, who played a prominent role in the split of the Independent Labour Party from the Labour Party. Living in Dumbarton, Irwin worked as a boilermaker, and became active in the United Society of Boilermakers. He also joined the Independent Labour Party (ILP), which was affiliated to the Labour Party. He was elected to Dumbarton Town Council, and became a bailie. In addition, he was involved in the National Union of Unemployed Workers, serving as its treasurer.