Paul B. Mackenzie (born 1950) is a theoretical physicist at the Fermi National Accelerator Laboratory. He did graduate work in physics at Cornell University where he was a student of G. Peter Lepage. He is an expert on Lattice Gauge Theory. He is the chair of the Executive Committee of USQCD, the US collaboration for developing the necessary supercomputing hardware and software for quantum chromodynamics formulated on a lattice.