Alexander Henry Dennett (6 January 1903 – 4 December 1956) was an Australian politician.
He was born in Melbourne to John Dennett and Dorothy Neale and became an Anglican lay preacher in Gippsland before serving in World War I.
During World War II he served in the Middle East and the Pacific, and received the rank of lieutenant-colonel.
He briefly held the Labour and Decentralisation portfolios in December 1948, and remained on the front bench until 1950.
He was Deputy Premier and Minister of Forests, Conservation and Immigration in the seventy-hour Hollway ministry that followed that action, and served as deputy of the group that became the Victorian Liberal Party until 1955, when he lost his seat.