| Simon L. Adler | |
| Office: | Judge of the United States District Court for the Western District of New York |
| Term Start: | May 19, 1927 |
| Term End: | May 23, 1934 |
| Appointer: | Calvin Coolidge |
| Predecessor: | Seat established by 44 Stat. 1370 |
| Successor: | Harlan W. Rippey |
| State Assembly1: | New York |
| District1: | Monroe County, 2nd |
| Term Start1: | January 1, 1911 |
| Term End1: | December 31, 1926 |
| Predecessor1: | James L. Whitley |
| Successor1: | Harry J. McKay |
| Birth Name: | Simon Louis Adler |
| Birth Date: | 30 August 1867 |
| Birth Place: | Seneca Falls, New York, U.S. |
| Education: | Cornell University (B.L.) Harvard Law School |
Simon Louis Adler (August 30, 1867 – May 23, 1934) was a United States district judge of the United States District Court for the Western District of New York.
Born on August 30, 1867, in Seneca Falls, New York, Adler received a Bachelor of Laws from Cornell University in 1889, and graduated from Harvard Law School in 1892. He practiced law in Rochester, New York. Adler was a member of the New York State Assembly (Monroe Co., 2nd D.) in the 134th New York State Legislature through the 149th New York State Legislature, from 1911 to 1926, and was Chairman of the Committee on Banks in 1915, and Majority Leader from 1916 to 1926.
Adler received a recess appointment from President Calvin Coolidge on May 19, 1927, to the United States District Court for the Western District of New York, to a new seat authorized by 44 Stat. 1370. He was nominated to the same position by President Coolidge on December 6, 1927. He was confirmed by the United States Senate on January 16, 1928, and received his commission the same day. His service terminated on May 23, 1934, due to his death.