Josiah Augustus "Si" Spaulding (December 21, 1922 – March 27, 1983) was an American businessman, attorney, and politician.

Spaulding graduated from the Hotchkiss School and Yale University in 1947, where he was a member of Skull and Bones.

He served three years as a pilot for the US Marine Corps during World War II and was discharged as a first lieutenant.

He was the Republican nominee for United States Senator in 1970 and Massachusetts Attorney General in 1974.

Spaudling was a partner in the Boston law firm of Bingham Dana & Gould.