Hiram Merrill (January 14, 1829 – September 5, 1908) was an American businessman and Wisconsin pioneer. He was the 18th mayor of Janesville, Wisconsin, and a member of the Wisconsin State Assembly.

Merrill was born on January 14, 1829, in Adams, New York, and came to what is now Milwaukee, Wisconsin, in 1837, where his father ran the Traveler's Inn at Walker's Point. Hiram worked in his father's shipyard, then headed west in 1849 for the California gold rush, where he sold water for hydraulic mining.^[1] On October 20, 1856, he married Louise Ballard.^[2] Merrill and his wife were Episcopalians. They had four children. He died on June 9, 1893.

In 1866 the Merrills settled in Janesville, Wisconsin, where Hiram gained control of the New Gas Light Company.^[1] He was elected to the Assembly in 1874, defeating incumbent John Winans, who later became a member of the United States House of Representatives. Other positions Merrill held include Mayor of Janesville. He was an Independent Republican.^[3]