Canadian financier and shipbuilder whose contribution of at least $300,000 to the Conservative Party campaign in 1872 precipitated the Pacific Scandal that brought down Sir John Macdonald (Macdonald, Sir John)'s government.

Allan immigrated to Canada in 1826 and in 1831 began work for a general merchandising company with shipping interests in Montreal. By 1839 he was a senior partner, and by 1853 he and his brother Andrew owned their own steamship company, eventually called the Allan Line, and conducted shipping between Montreal, Glasgow, and Liverpool. His services to Canadian commerce won him a knighthood in 1871.

In 1872 the Canadian government gave Allan the transcontinental railway charter for his Canadian Pacific Railway. It was later revealed, however, that, as a member of a Chicago financial syndicate, he had subsidized Macdonald's Conservative Party election campaign. The subsequent scandal not only discredited Macdonald's government but also led to the dissolution of Allan's railway company.