William Ernest Mason (July 7, 1850 – June 16, 1921) was a Republican U.S. Representative and Senator from Illinois.

After graduating, he taught at Bentonsport Academy, which he had previously attended.

After studying law, he moved to Chicago in 1872 and was admitted to the bar.

Following his defeat in 1890, he returned to law practice in Chicago in 1891 but was elected to the U.S. Senate in 1896.

Look out for tea parties"[2] On April 5, 1917, he was one of 50 representatives who voted against declaring war on Germany.