The Rural Municipality of Griffin No. 66 (2016 population: ) is a rural municipality (RM) in the Canadian province of Saskatchewan within Census Division No. 2 and Division No. 1.
The RM of Hastings No. 66 was originally incorporated as a rural municipality on December 13, 1909. Its name was changed to the RM of Griffin No. 66 on January 30, 1910.
The following unincorporated communities are within the RM.
In the 2021 Census of Population conducted by Statistics Canada, the RM of Griffin No. 66 had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of , it had a population density of in 2021.
In the 2016 Census of Population, the RM of Griffin No. 66 recorded a population of living in of its total private dwellings, a change from its 2011 population of . With a land area of , it had a population density of in 2016.
The RM of Griffin No. 66 is governed by an elected municipal council and an appointed administrator that meets on the second Tuesday of every month. The reeve of the RM is Stacey Lund while its administrator is Tawnya Moore. The RM's office is located in Griffin.