Sidnie Milana Manton, FRS (4 May 1902 — 2 January 1979) was a British entomologist.
Sidnie Milana Manton was born in Kensington, London the daughter of a descendant of French aristocracy and a dentist. Her sister was the botanist Professor Irene Manton FRS. She was educated at the Froebel Demonstration School and at St. Paul's Girls' School before joining Girton College, Cambridge in 1921.
Manton joined Cambridge University and worked on the evolution of the arthropods, publishing "The Arthropoda: Habits, Functional Morphology and Evolution" in 1977.
She was elected a Fellow of the Royal Society in March 1948.
Manton married John Philip Harding in 1937. They had one son and one daughter.