| William Kernahan Thomas | |
| Office: | Senior Judge of the United States District Court for the Northern District of Ohio |
| Term Start: | February 15, 1981 |
| Term End: | March 20, 2001 |
| Office1: | Judge of the United States District Court for the Northern District of Ohio |
| Term Start1: | March 7, 1966 |
| Term End1: | February 15, 1981 |
| Appointer1: | Lyndon B. Johnson |
| Predecessor1: | Paul Jones |
| Successor1: | John William Potter |
| Birth Name: | William Kernahan Thomas |
| Birth Date: | 15 February 1911 |
| Birth Place: | Columbus, Ohio |
| Death Place: | Cleveland, Ohio |
| Education: | Ohio State University (B.A.) Ohio State University Moritz College of Law (J.D.) |
William Kernahan Thomas (February 15, 1911 – March 20, 2001) was a United States district judge of the United States District Court for the Northern District of Ohio.
Born in Columbus, Ohio, Thomas received a Bachelor of Arts degree from Ohio State University in 1932 and a Juris Doctor from Ohio State University Moritz College of Law in 1935. He was in private practice in Cleveland, Ohio from 1935 to 1944. He was a United States Naval Reserve Lieutenant during World War II, from 1944 to 1946. He was in private practice in Cleveland from 1946 to 1950. He was a judge of the Court of Common Pleas for Geauga County, Ohio from 1950 to 1953. He was a judge of the Court of Common Pleas for Cuyahoga County, Ohio from 1953 to 1966.
Thomas was nominated by President Lyndon B. Johnson on January 19, 1966, to a seat on the United States District Court for the Northern District of Ohio vacated by Judge Paul Jones. He was confirmed by the United States Senate on March 4, 1966, and received his commission on March 7, 1966. He assumed senior status on February 15, 1981. Thomas served in that capacity until his death on March 20, 2001, in Cleveland.