William Berrian Vail, PC (December 19, 1823 – April 10, 1904) was a Canadian businessman and politician.

He represented Digby County in the Nova Scotia House of Assembly from 1867 to 1874.

He resigned because of a conflict of interest in the 1877 but returned to parliament in 1882 where he served as an opposition MP until he lost his seat once again in the 1887 general election.

His brother Edwin Arnold Vail served in the New Brunswick assembly.

This article about a Member of the Nova Scotia House of Assembly is a stub.