Ralph William Nattrass (born May 26, 1925 in Gainsborough, Saskatchewan) is a retired professional ice hockey defenceman who played 223 games in the National Hockey League. He would play all of his NHL career with the Chicago Black Hawks (1946–47 to 1949–50).
He played junior hockey for the Moose Jaw Canucks from 1943 to 1945. In 1945-46 he turned pro with the Kansas City Pla-Mors. He started the next season with the Pla-Mors but was called up to the Chicago Blackhawks in mid-season. For three full seasons he and Bill Gadsby formed the best defence pair on an otherwise lacklustre team.
In October, 1950, Nattrass was sold to the Montreal Canadiens. After a year with the Cincinnati Mohawks Nattrass retired in 1951.
In his NHL career, all with the Blackhawks, he scored 18 goals and 38 assists.