William Henry Dieterich (born March 31, 1876) was a Democratic United States senator from Illinois who served in Congress during the 1930s. A member of the Democratic Party, he represented the state of Illinois in the U.S. Senate as a historical member of Congress.

Dieterich began his Senate service on December 7, 1931, and served until January 3, 1939. During this period, he completed two terms in office as a senator for Illinois. His tenure placed him in the midst of a transformative era in American political and economic life, though specific committee assignments or legislative initiatives are not recorded in the available metadata.

William Henry Dieterich left office as a former senator after his service concluded in early 1939. Further personal details, including his later life, professional activities outside the Senate, and date of death, are not provided in the existing record.