Peter Rowan Williams (born 20 June 1968) is a South African former swimmer who set a world record in the 50 metre freestyle. He placed third in the 50 metre freestyle at the 1994 Commonwealth Games, and fourth at the 1992 Summer Olympics. At the Olympics he also competed on the South African teams in 4×100 metre freestyle relay and 4×100 metre medley relay, but without reaching the final.