Arthur Oliver Lonsdale Atkin (31 July 1925 – 28 December 2008), who published under the name A. O. L. Atkin, was a British mathematician. As an undergraduate during World War II, Atkin worked at Bletchley Park cracking German codes. He received his Ph.D. in 1952 from the University of Cambridge, where he was one of John Littlewood's research students. During 1964–1970, he worked at the Atlas Computer Laboratory at Chilton, computing modular functions. Toward the end of his life, he was Professor Emeritus of mathematics at the University of Illinois at Chicago.