William Ellsworth Glasscock (December 13, 1862 – April 12, 1925) was an American politician who served as the 13th Governor of West Virginia as a Republican from 1909 to 1913.
Glasscock was born in Monongalia County, West Virginia and graduated from West Virginia University. In 1888, he married Mary Miller. In 1903 he was admitted to the bar. Glasscock worked as an attorney for Senator Stephen B. Elkins.
In his last year as governor, he declared martial law three times, sending troops to quell violent coal strikes.
Glasscock returned to practicing law. He died in Morgantown, West Virginia and was buried in Oak Grove Cemetery.