William Yerger Humphreys (September 9, 1890 – February 26, 1933) was a U.S. Representative from Mississippi, son of Benjamin G. Humphreys II.
Born in Greenville, Washington County, Mississippi, Humphreys attended the public schools and Sewanee Grammar School, Sewanee, Tennessee. He studied law at George Washington University, Washington, D.C. from 1911 to 1914, while in the employ of the United States House of Representatives as assistant superintendent of the House document room. He was admitted to the bar on June 1, 1914, and commenced practice in Greenville, Mississippi. He served as first lieutenant in the Chemical Warfare Service of the United States Army during the First World War.
Humphreys was elected as a Democrat to the Sixty-eighth Congress to fill the vacancy caused by the death of his father, Benjamin G. Humphreys, and served from November 27, 1923, to March 3, 1925. He was not a candidate for renomination in 1924. He resumed the practice of law in Greenville, Mississippi.
Humphreys was elected prosecuting attorney of Washington County in 1928 and served until his death in Greenville, Mississippi, on February 26, 1933. He was interred in Greenville Cemetery.