Albert Brydges Farn (1841–1921) was a British amateur entomologist, chiefly remembered nowadays for a letter he wrote on 1878 to Charles Darwin describing industrial melanism in the annulet moth (Charissa obscurata). Farn was a respected entomologist. In 1880 he revised and extended The Insect Hunter's Companion, and in 1890 he was elected a fellow of the Entomological Society. The extensive collection of Lepidoptera which he had amassed was dispersed after his death.