Simon Louis Adler (August 30, 1867 – May 23, 1934) was a United States federal judge.
Born in Seneca Falls, New York, Adler received a B.L. from Cornell University in 1889, and graduated from Harvard Law School in 1892. He was entered private practice in Rochester, New York in 1892 to the present, and from 1911 to 1926 he was a Representative in the New York State Assembly, including a ten-year stint as majority leader beginning in 1916.
On May 19, 1927, Adler received a recess appointment from President Calvin Coolidge to a new seat on the United States District Court for the Western District of New York created by 44 Stat. 1370. Formally nominated on December 6, 1927, he was confirmed by the United States Senate on January 16, 1928, and received his commission the same day. Adler served until his death.