William Joseph Hynes (March 31, 1843 – April 2, 1915) was an American newspaperman, lawyer, and politician who served one term as a U.S. Representative from Arkansas from 1873 to 1875.

His mother died in 1864 and Hynes relocated to Nashville, Tennessee, to study law with attorney John O'Neill.

He attended Columbian University's law school (now George Washington University Law School) in Washington, D.C., while working as a newspaper reporter and secretary for Benjamin F. Rice, a United States senator from Arkansas.

He retired from the practice of law in 1910 and moved to Los Angeles, California, where he remained until his death.

This article incorporates public domain material from the Biographical Directory of the United States Congress