Pieter Timotheus "Tim" de Zeeuw (born 1956, Sleen) is a Dutch astronomer specializing in the formation, structure and dynamics of galaxies. He was educated atLeiden, gaining a degree in mathematics in 1976 and one in astronomy in 1977. He graduated from Leiden with a PhD in astronomy in 1984. After stints in the USA at the Institute for Advanced Study in Princeton and at Caltech, he returned to the Netherlands in 1990 to become Professor of Theoretical Astronomy at Leiden.