Günter Matthias Ziegler (born 19 May 1963) is a German mathematician who has been working as president of the Free University of Berlin since 2018.

After postdoctoral positions at the University of Augsburg and the Mittag-Leffler Institute, he received his habilitation in 1992 from Technische Universität Berlin], which he joined as a professor in 1995.

Ziegler was awarded the one million Deutschmark Gerhard Hess Prize [de] by the Deutsche Forschungsgemeinschaft (DFG) in 1994 and the 1.5 million Deutschmark Gottfried Wilhelm Leibniz Prize, Germany's highest research honor, by the DFG in 2001.

[3][5] In 2006 Ziegler became president of the German Mathematical Society for a two-year term.

In 2018 he received the Leroy P. Steele Prize for Mathematical Exposition (jointly with Martin Aigner) for Proofs from THE BOOK.