Arthur Loomis Sanborn (November 17, 1850 – October 18, 1920) was a United States federal judge.
Born in Brasher Falls, New York, Sanborn received an LL.B. from the University of Wisconsin Law School in 1880. He was a register of deeds for Walworth County, Wisconsin from 1875 to 1879, and was in private practice from 1880 to 1905.
On January 6, 1905, Sanborn was nominated by President Theodore Roosevelt to a seat on the United States District Court for the Western District of Wisconsin vacated by Romanzo Bunn. Sanborn was confirmed by the United States Senate on January 9, 1905, and received his commission the same day. Sanborn served in that capacity until his death, in 1920.