Lillian Beatrix Pierce is a mathematician whose research connects number theory with harmonic analysis. She was one of the first mathematicians to prove nontrivial upper bounds on the number of elements of finite order in an ideal class group.She won the 2018 Sadosky Prize for research that "spans and connects a broad spectrum of problems ranging from character sums in number theory to singular integral operators in Euclidean spaces" including in particular "a polynomial Carleson theorem for manifolds". She is a professor of mathematics at Duke University, and a von Neumann Fellow at the Institute for Advanced Study.