Yitzhak Katznelson (Hebrew: יצחק קצנלסון; born 1934) is an Israeli mathematician.
Katznelson was born in Jerusalem. He received his doctoral degree from the University of Paris in 1956. He is presently a professor of mathematics at Stanford University.
He is the author of An Introduction to Harmonic Analysis, which won the Steele Prize for Mathematical Exposition in 2002.