Al Richardson (20 December 1941 - 22 November 2003) was a British Trotskyist historian and activist.
Born in Woolley Colliery, a pit village near Barnsley, Richardson studied theology at the University of Hull before becoming a lecturer at the University of Exeter. He joined the Communist Party of Great Britain, but left after reading Isaac Deutscher's biography of Leon Trotsky. Convinced of Trotskyism, he joined the Socialist Labour League (SLL), and resigned from the faculty at Exeter to become a history teacher in Forest Hill School, South London. He soon quit the SLL to join the rival International Marxist Group (IMG), and became prominent in the Vietnam Solidarity Campaign.
Despite hitchhiking to Paris to join the events of May 1968, Richardson was part of a small group which rejected the IMG's turn away from trade unions and the labour movement to work in the student movement. He became a founder member of the break-away Revolutionary Communist League, and was elected to its leadership, but in 1973 he left the League.
From the mid-1970s, Richardson focussed his attention on recording the history of Trotskyism in Britain. He began interviewing veterans of the movement, and with Sam Bornstein, published three books on the topic through their "Socialist Platform" publishing house. In 1988 they founded the journal Revolutionary History, dedicated to the history of the anti-Stalinist left.