William J. Fisk (June 25, 1833-March 1, 1909) was an American politician who was a member of the Wisconsin State Assembly.
Fisk was born on June 25, 1833 in Brunswick, Ohio. Sources have differed on his residential history, but he apparently settled in Fort Howard, Wisconsin in 1853. There, his father, Joel S. Fisk, became Postmaster. Fisk would operate a shingle mill before becoming a lumberman and bank president and director.
On January 8, 1855, Fisk married Mary J. Driggs. They would have four sons, including Wilbur D. Fisk, who would become Treasurer of Fort Howard. Mary's sister, Martha, would marry Samuel Ryan, Jr.. After Mary's death in April 1903, Fisk married Hattie Trowel. He died on March 1, 1909.
Fisk was a member of the Assembly from 1875 to 1877. Previously, he had been Postmaster of Fort Howard from 1862 to 1865. He was a Republican.