Peter Manfred Gruber (28 August 1941, Klagenfurt – 7 March 2017, Vienna) was an Austrian mathematician working in geometric number theory as well as in convex and discrete geometry.
Gruber obtained his PhD at the University of Vienna in 1966, under the supervision of Nikolaus Hofreiter. From 1971, he was Professor at the University of Linz, and from 1976, at the TU Wien. He was a member of the Austrian Academy of Sciences, a foreign member of the Russian Academy of Sciences, and a corresponding member of the Bavarian Academy of Sciences and Humanities.
His past doctoral students include Monika Ludwig.