Rudolf Haag (* 1922 in Tübingen, Germany) is a German physicist. He is best known for his contributions to the axiomatic formulation of quantum field theory, namely the Haag-Kastler axioms, and a central no-go theorem in QFT, Haag's theorem.

Dr. Rudolf Haag as Visiting Professor of Physics for the Fall term 1970-71 (partial affiliation).

Haag studied Physics at Technische Hochschule Stuttgart from 1948 to 1954 and then working on his dissertation in Munich. 1956 to 1957 he was at Max-Planck-Institut Göttingen. After doing one year each as visiting professor at Princeton University and University of Marseille, he was professor of physics at the University of Illinois for six years until 1966.

After that and until his retirement he held a chair for theoretical physics at the University of Hamburg.

In 1965 he founded the journal Communications in Mathematical Physics .

He was awarded the Max Planck medal in 1970 and the Poincaré prize of the International Association of Mathematical Physics in 1997.