What was the name of Charles Darwin's youngest child who died in infancy?

Charles Darwin’s youngest child who died in infancy was Charles Waring Darwin.

Born on 6 December 1856, Charles Waring was the tenth and last child of Charles Darwin and Emma Darwin. He died of scarlet fever on 28 June 1858, aged about eighteen months. His death came during the emotionally difficult period when Darwin was preparing the public presentation of his work on natural selection.

Charles Waring was described by his family as having significant developmental difficulties: he never learned to walk or talk. Later writers have suggested that he may have had Down syndrome, though that diagnosis was not available in the nineteenth century and should be treated as a retrospective interpretation rather than a confirmed contemporary medical diagnosis.

He was one of two Darwin children who died in infancy. Mary Eleanor Darwin died in 1842 at only a few weeks old, while Anne Elizabeth Darwin died in 1851 at the age of ten. Charles Waring’s death also explains why Darwin did not attend the Linnean Society meeting on 1 July 1858, where extracts from his work and Wallace’s essay were jointly presented.