William Cary Van Fleet (March 24, 1852–September 3, 1923) was a United States federal judge.
Born in Maumee, Ohio, Van Fleet read law to enter the bar in 1873. He was an assistant district attorney of Sacramento County, California from 1878 to 1879. He was a California State Assemblyman from 1881 to 1882. He was the Director of California State Prisons from 1883 to 1884. He was a judge of the Superior Court of California from 1884 to 1892. He was an Associate Justice of the Supreme Court of California from 1894 to 1899.
Van Fleet was a federal judge on the United States District Court for the Northern District of California. Van Fleet received a recess appointment from President Theodore Roosevelt on April 2, 1907, to a new seat created by 34 Stat. 1253; nominated on December 3, 1907. He was confirmed by the United States Senate on December 17, 1907, and received his commission the same day. Van Fleet died in office on September 3, 1923.