| Robert Reasoner Nevin | |
| Office: | Chief Judge of the United States District Court for the Southern District of Ohio |
| Term Start: | 1948 |
| Term End: | 1952 |
| Predecessor: | Office established |
| Successor: | Mell G. Underwood |
| Office1: | Judge of the United States District Court for the Southern District of Ohio |
| Term Start1: | January 21, 1929 |
| Term End1: | December 31, 1952 |
| Appointer1: | Calvin Coolidge |
| Predecessor1: | Smith Hickenlooper |
| Successor1: | Lester LeFevre Cecil |
| Birth Name: | Robert Reasoner Nevin |
| Birth Date: | 2 August 1875 |
| Birth Place: | Dayton, Ohio |
| Education: | Ohio State University Cincinnati Law School read law |
Robert Reasoner Nevin (August 2, 1875 – December 31, 1952) was a United States district judge of the United States District Court for the Southern District of Ohio.
Born in Dayton, Ohio, Nevin attended Ohio State University and Cincinnati Law School (now the University of Cincinnati College of Law), but read law to enter the bar in 1898. He served as a lieutenant in the United States Army during the Spanish–American War, and was in private practice in Dayton from 1898 to 1903. He was prosecuting attorney of Montgomery County, Ohio from 1906 to 1919.
On January 5, 1929, Nevin was nominated by President Calvin Coolidge to a seat on the United States District Court for the Southern District of Ohio vacated by Judge Smith Hickenlooper. Nevin was confirmed by the United States Senate on January 21, 1929, and received his commission the same day. He served as Chief Judge from 1948 until his death on December 31, 1952.