Walter Rudin (May 2, 1921 – May 20, 2010) was an American mathematician and professor of Mathematics at the University of Wisconsin–Madison.
He is known for three books on mathematical analysis: Principles of Mathematical Analysis, Real and Complex Analysis, and Functional Analysis. The first (affectionately referred to as "Baby Rudin") was written when Rudin was a Moore instructor at MIT for his undergraduate analysis course and is widely used as a textbook for undergraduate courses in analysis.