Alfred Duggan (born Alfredo León Duggan; 1903–1964) was an Argentine-born English historian and archaeologist, and a well-known historical novelist in the 1950s. His novels are known for meticulous historical research.

Though brought up in Britain, he was born Alfredo León Duggan in Lomas de Zamora, Buenos Aires, Argentina, to a family of wealthy landowners of Irish descent. His family moved to Britain when he was two years old. His father, Alfredo Huberto Duggan, a first generation Irish Argentine, was appointed in 1905 to the Argentine Legation in London, and died in 1915. In 1917, his mother, the Alabama-born Grace Elvira Hinds, daughter of the U.S. Consul General in Rio de Janeiro, became the second wife of Lord Curzon, the former Viceroy of India.

Duggan and his brother, Hubert (1904–1943), were brought up in Britain at Curzon's seats, and were educated first at Wixenford and Eton. Thereafter Alfred went to Balliol College at Oxford, where he became acquainted with Anthony Powell and Evelyn Waugh. He often features in Waugh's letters and diaries of the period, and his South American background may have influenced the character of Anthony Blanche in Brideshead Revisited, though Waugh described the character as "2/3 Brian [Howard] and 1/3 Harold Acton. People think it was all Harold, who is a much sweeter and saner man [than Howard]."

Alfred Duggan kept a car while at Oxford, one of the few students with sufficient funds and influence to do so; the University Statutes prohibited undergraduates from keeping a car within a certain distance of the town centre at Carfax, and so Duggan kept his, an early Rolls-Royce, just outside the limit of the jurisdiction of the University Proctors, and would regularly drive himself and his friends to and from London during the social season. At Oxford he was part of the Hypocrites' Club.

During 1938–1941, Duggan served with the London Irish Rifles, with active service in the Norwegian Campaign. For the rest of the Second World War he worked in an aeroplane factory.

In 1953, Duggan married Laura Hill. They went to live in Ross-on-Wye, where he died in April 1964. According to a review by John Derbyshire, Duggan "in later years, his inheritance gone... adjusted philosophically to his changed circumstances, living a bookish and domestic life utterly at odds with the extravagant dissipation of his youth. He seems to have been a devoted husband and parent, and a loyal friend."

Duggan's novels are known for their basis of meticulous historical research. He also wrote popular histories of Ancient Rome and the Middle Ages. Knight with Armour, his first novel, appeared in 1946. He visited practically every place and battlefield described, since he was also an archaeologist, having worked on excavations in Istanbul during the 1930s.

Unlike many historical novelists, he does not idealise his subjects. A few characters are noble, some rather nasty, many mixed in their motives. Some of the novels can be seen as funny, in a dry noir style. A recurring theme is the slow moral corruption of a character who begins with an exalted opinion of himself as noble, wise and brave, but gradually compromises himself morally.