| Nathaniel Ewing | |
| Office: | Judge of the United States District Court for the Western District of Pennsylvania |
| Term Start: | September 25, 1906 |
| Term End: | January 31, 1908 |
| Appointer: | Theodore Roosevelt |
| Predecessor: | Joseph Buffington |
| Successor: | James Scott Young |
| Birth Name: | Nathaniel Ewing |
| Birth Date: | 17 June 1848 |
| Birth Place: | Uniontown, Pennsylvania |
Nathaniel Ewing (June 17, 1848 – March 28, 1914) was a United States district judge of the United States District Court for the Western District of Pennsylvania.
Born in Uniontown, Pennsylvania, Ewing received an Artium Baccalaureus degree from Princeton University in 1869 and an Artium Magister degree from the same institution in 1872. He was in private practice in Uniontown from 1871 to 1887. He was a Judge of the 14th Judicial District of Pennsylvania from 1887 to 1899, returning to private practice in Uniontown from 1900 to 1906.
Ewing received a recess appointment from President Theodore Roosevelt on September 25, 1906, to a seat on the United States District Court for the Western District of Pennsylvania vacated by Judge Joseph Buffington. He was nominated to the same position by President Roosevelt on December 3, 1906. He was confirmed by the United States Senate on December 11, 1906, and received his commission the same day. His service terminated on January 31, 1908, due to his resignation.
Ewing was then Chairman of the Pennsylvania State Railroad Commission from 1908 to 1913, and Chairman of the Public Service Commission of Pennsylvania from 1913 to 1914. He died on March 28, 1914.