Denzil Dean Harber (25 January 1909, Streatham, – 31 August 1966) was an early British Trotskyist leader and later in his life a prominent British ornithologist. Denzil Dean Harber was born at 25 Fairmile Avenue, Streatham on 25 January 1909. His father was a ship's carpenter turned architect, his mother the daughter of a successful south London butcher. During the First World War the family moved to Sussex , where they lived in a succession of houses at Climping, Lewes, and Eastbourne and finally at the Black Mill, Ore near Hastings.