Margaret Hilary Millington (22 March 1944 – 5 March 1973) was an English-born mathematician.^[1]

She was born Margaret Hilary Ashworth in Halifax, Yorkshire, the daughter of the local assistant head postmaster, and was educated there. She continued her studies at St Mary's College, Durham^[2] and went on to Oxford University, where she earned a PhD in 1968 with A. O. L. Atkin as her advisor.^[3] Also, in 1968, she married Lieutenant A.H. Millington,^[2] who was part of the Royal Electrical and Mechanical Engineers.^[1] She was awarded a two-year Science Research Council Fellowship which allowed her to pursue research at any university. During her husband's two-year posting in Germany, she taught mathematics at an Army Education Centre there.^[1]

She died in Germany due to a brain tumour at the age of 28.^[2]

Although her career was cut short, in 1983, the London Mathematical Society organized a symposium on modular forms. During the symposium, the importance of her doctoral thesis and post-doctoral research became clear. The work that she had started during her fellowship was picked up and pursued by other mathematicians, leading to a resurgence in the field.^[1] Her research had dealt with modular forms, as well as subgroups of the modular group.^[1]

In a tribute to Millington, Atkin said "I have no doubt that, had she lived, she would have made exciting original contributions to a field which has at last come into its own again, after nearly a quarter century in the doldrums, and where there are now at least twenty first rate people of her generation working actively."^[1]