William G. McCallum (born 1956 in Sydney, Australia)^[1] is a retired University Distinguished Professor of Mathematics at the University of Arizona. His professional interests include arithmetical algebraic geometry and mathematics education.

McCallum received a bachelor's degree from the University of New South Wales in 1977,^[2] and his Ph.D. in Mathematics from Harvard University in 1984, under the supervision of Barry Mazur.^[3]

He was a postdoctoral researcher at the University of California, Berkeley and the Mathematical Sciences Research Institute in Berkeley before joining the University of Arizona in 1987.^[1] He became University Distinguished Professor from 2006 until his retirement in 2018, and headed the Department of Mathematics from 2009 to 2013.^[2]

McCallum helped found the Harvard Calculus Consortium with other mathematicians including Andrew M. Gleason and Deborah Hughes Hallett.^[4] He led the development of the Common Core standards for mathematics from 2009 until the standards were first released in 2010.^[5] In 2014 he founded a company, eventually known as Illustrative Mathematics, to develop teaching resources for the mathematics standards that he helped develop.^[6]

In 2012, McCallum Fellow of the American Mathematical Society.^[7] In the same year he received the inaugural Mary P. Dolciani Award for distinguished contributions to mathematical education, administered by the Mathematical Association of America,^[8] and the AMS Distinguished Public Service Award of the American Mathematical Society, "for his energetic and effective efforts in promoting improvements to mathematics education"^[4]