Ken Ono (born 20 March 1968) is a Japanese-American mathematician who specializes in number theory, especially in integer partitions, modular forms, Umbral moonshine, the Riemann Hypothesis and the fields of interest to Srinivasa Ramanujan. He was the Manasse Professor of Letters and Science and the Hilldale Professor of Mathematics at the University of Wisconsin–Madison, and also was formerly the Asa Griggs Candler Professor of Mathematics at Emory University.