David Masser

David William Masser (born 8 November 1948) is Professor of Mathematics at the University of Basel, in Basel, Switzerland. He obtained his Ph.D. from University of Cambridge in 1974 on the topic of Elliptic Functions and Transcendence.

Before his appointment at the Mathematics Institute in Basel, Masser taught at the University of Michigan. He was an invited speaker at the International Congress of Mathematicians at Warsaw in 1983. He is known for his work in number theory, and was elected to the Royal Society in 2005.

Along with Joseph Oesterlé, Masser formulated the abc conjecture in 1985. It has been stated that this conjecture "is the most important unsolved problem in Diophantine analysis".