Sir George Howard Darwin KCB FRS (9 July 1845 – 7 December 1912) was an English astronomer and mathematician.

George Darwin was born at Down House, Kent, the second son and fifth child of Charles and Emma Darwin. He studied under Charles Pritchard, and entered St John's College, Cambridge in 1863, though he soon moved to Trinity College, where his tutor was Edward John Routh. He graduated as second wrangler in 1868, when he was also placed second for the Smith's Prize and was appointed to a college fellowship. He was admitted to the bar in 1872, but returned to science. He was elected a Fellow of the Royal Society in June, 1879 and won their Royal Medal in 1884 and their Copley Medal in 1911. He delivered their Bakerian Lecture in 1891 on the subject of "tidal prediction".

In 1883 he became Plumian Professor of Astronomy and Experimental Philosophy at the University of Cambridge. He studied tidal forces involving the Sun, Moon, and Earth, and formulated the fission theory of Moon formation.

He won the Gold Medal of the Royal Astronomical Society in 1892, and also later (1899–1901) served as president of that organization.

Darwin married Martha (Maud) du Puy of Philadelphia in 1884; she died on February 6, 1947. They had two sons and two daughters:

• Gwen Raverat (1885–1957), artist.
• Charles Galton Darwin (1887–1962), physicist.
• Margaret Elizabeth Darwin (1890–1974), married Sir Geoffrey Keynes.
• William Robert Darwin (1894–1970)
• Father of George Erasmus Darwin (1927-)
• Grandfather of Chris Darwin (1961-) and Sarah Darwin (1964-)

He is buried in Trumpington Extension Cemetery in Cambridge with his wife Lady Maud Darwin and their daughter Gwen (Raverat), but his brothers Sir Francis Darwin and Sir Horace Darwin are interred in the Parish of the Ascension Burial Ground.

Sir George Darwin was elected an Honorary Fellow of the Astronomical and Physical Society of Toronto on 1894-01-09. He wrote to the Society, "I shall have much pleasure in accepting the Honourary Membership of the Toronto Astronomical and Physical Society if my nomination is accepted by the Society. I beg leave to thank the Society in advance for the honour which they propose to confer on me."

The asteroid (1991) Darwin is dedicated to Charles Darwin, and also George Howard Darwin.