William Emerson Brock (March 14, 1869 – August 5, 1950) was a Democratic United States Senator from Tennessee from 1929 to 1931.

On September 2, 1929, the Governor of Tennessee, Henry Hollis Horton, appointed Brock to the vacancy in the U.S. Senate caused by the death of Lawrence D. Tyson; Horton had first offered the appointment to former Senator Luke Lea, who declined.

He did not run for the full six-year term that was on the ballot at the same time, and his service as a U.S. senator ended on March 3, 1931.

After leaving the Senate, Brock returned to his Chattanooga candy manufacturing business and remained involved in its operation until his death in 1950.

This article incorporates public domain material from the Biographical Directory of the United States Congress