| John Percy Nields | |
| Office: | Senior Judge of the United States District Court for the District of Delaware |
| Term Start: | September 30, 1941 |
| Term End: | August 26, 1943 |
| Office1: | Judge of the United States District Court for the District of Delaware |
| Term Start1: | July 3, 1930 |
| Term End1: | September 30, 1941 |
| Appointer1: | Herbert Hoover |
| Predecessor1: | Hugh M. Morris |
| Successor1: | Paul Conway Leahy |
| Office2: | United States Attorney for the District of Delaware |
| President2: | Theodore Roosevelt William Howard Taft Woodrow Wilson |
| Term Start2: | 1903 |
| Term End2: | 1916 |
| Predecessor2: | William Michael Byrne |
| Successor2: | Charles F. Curley |
| Birth Name: | John Percy Nields |
| Birth Date: | 7 August 1868 |
| Birth Place: | Wilmington, Delaware, U.S. |
| Death Place: | Nahant, Massachusetts, U.S. |
| Education: | Harvard University (AB, LLB) |
| Battles: | World War II |
| Unit: | Ordnance Corps |
John Percy Nields (August 7, 1868 – August 26, 1943) was a United States district judge of the United States District Court for the District of Delaware.
Born in Wilmington, Delaware, Nields received an Artium Baccalaureus degree from Harvard College in 1889 and a Bachelor of Laws from Harvard Law School in 1892.
Nields worked in private practice in Wilmington from 1892 to 1903. He was the United States attorney for the District of Delaware from 1903 to 1916, thereafter returning to private practice in Wilmington in 1930. He was a captain in the United States Army Ordnance Corps during World War II in 1918.
On June 20, 1930, Nields was nominated by President Herbert Hoover to a seat on the United States District Court for the District of Delaware vacated by Judge Hugh M. Morris. Nields was confirmed by the United States Senate on July 3, 1930, and received his commission the same day. He assumed senior status on September 30, 1941, serving in that capacity until his death on August 26, 1943, in Nahant, Massachusetts.