Alexander Francis Lydon (1836-1917) was an English watercolour artist, illustrator and engraver, best known for his natural history studies and landscapes.

Born in Newbridge, Ireland, Lydon was the eldest of at least six children in a family of travellers. His father, Patrick Lydon, was a Chelsea Pensioner and Relieving Officer of Driffield Union, and his mother, Elizabeth Gwillym, was the daughter of a Lutheran pastor.

Lydon's artistic journey began when he was apprenticed to the printer Benjamin Fawcett at a young age, allowing him to work on numerous projects that came Fawcett's way.

Lydon's work was particularly associated with the publisher Groombridge and Sons in the 1860s and 1870s, for whom he illustrated numerous books ranging from natural history to classics such as 'The Pilgrim's Progress' (1871).

He is best known for his natural history work, illustrating books such as 'Parrots in Captivity' (1884), 'Seaside Walks of a Naturalist' (1870), 'British Fresh Water Fishes' Vol.1 & 2 (1879) and 'Ferns British & Exotic' (1872).  'A Series of Picturesque Views of Seats of the Noblemen and Gentlemen of Great Britain and Ireland' (Vols 1-6) saw Lydon produce some detailed scenery work.

Alexander's grandson, Gerald Kenneth Lydon (1902–1988), known professionally as GK Lydon, was also a successful artist specialising in watercolours. He was elected a Fellow of the Royal Society of Arts in 1953.