William Alvin Massingill (November 28, 1863 – March 19, 1927), also known as Billy Massingill or W. A. Massingill, was an American businessman and politician who served as state legislator for the state of Oregon. He served one two-year term in the Oregon House of Representatives as a Republican legislator, representing a large rural district in south-central Oregon. He also ran a general store, sawmill, and a wool shipping warehouse in Lakeview, Oregon, and was that town's postmaster for several years.