Sir Horace Darwin, KBE, FRS (13 May 1851 – 22 September 1928), a son of the English naturalist Charles Darwin, was a civil engineer. Fellow of Trinity College, Cambridge.
Darwin was born in Down House in 1851, the fifth son and ninth child of the British naturalist Charles Darwin and his wife Emma, the youngest of their seven children that survived to adulthood.
He was educated at a private school in Woodbridge, Suffolk and at Trinity College, Cambridge, where he graduated BA in 1874. He founded the Cambridge Scientific Instrument Company in 1885 and was Mayor of Cambridge between 1896 and 1897. He was elected a Fellow of the Royal Society in 1903. He was knighted in 1918.
Darwin married Emma Cecilia "Ida" Farrer (1854–1946), daughter of Thomas Farrer, 1st Baron Farrer in January 1880, later Lady Ida Darwin and they had one son and two daughters:
His family home, "the Orchard", in Huntingdon Road, Cambridge, is now the site of Murray Edwards College.
He is buried at the Parish of the Ascension Burial Ground in Cambridge with his wife, Lady Ida Darwin; his brother Sir Francis Darwin is interred in the same graveyard. His other brother Sir George Darwin is buried in the Trumpington Extension Cemetery, Cambridge.