William Alexander Massey (October 7, 1856 – March 5, 1914) was an American politician who served as a member of the United States Senate from Nevada.

He moved to San Diego, California in 1886 and to Nevada in 1887, where he prospected, mined, and practiced law in Elko.

Massey was a member of the Nevada Assembly from 1892 to 1894, and was district attorney of Elko County from 1894 to 1896.

He moved to Reno, Nevada and resumed the practice of law, and was appointed as a Republican to the United States Senate by Governor Tasker Oddie, to fill the vacancy caused by the death of George S. Nixon.

He was defeated for election to the remainder of Nixon's term by Democrat Key Pittman.