William M. Blair (May 25, 1836 – June 17, 1919) was a farmer and political figure in Nova Scotia, Canada. He represented Colchester County in the Nova Scotia House of Assembly from 1878 to 1886 as a Liberal-Conservative member. His son was William Saxby Blair who followed in his father's footsteps in agricultural promotion, being the first supervisor of the Experimental Farm in Kentville, Nova Scotia from its creation in 1912 until his retirement in 1938.