Jess Myron Willard (December 29, 1881 – December 15, 1968) was an American world heavyweight boxing champion billed as the Pottawatomie Giant. He claimed the heavyweight title in 1915 by knocking out Jack Johnson.

Willard was known for size rather than skill, and though he held the championship for more than four years, he rarely defended it. In 1919, when he was 37 years old, he lost the title in an extremely one-sided loss by declining to come out for the fourth round against Jack Dempsey, who became a more celebrated champion. Soon after the bout, Willard began accusing Dempsey of using something with the effect of a knuckle duster. Dempsey did not grant Willard a return match, and at 42 years old he was KO'd, following which he retired from boxing, although for the rest of his life he continued to claim Dempsey had cheated. Ferdie Pacheco expressed the opinion in a book that the surviving photographs of Willard's face during the Dempsey fight indicate fractures to Willard's facial bones suggesting a metal implement, and show he was bleeding heavily. The matter has never been resolved, with contemporaneous ringside sports journalist reporting in the New York Times that Willard spat out at least one tooth and was "a fountain of blood" increasingly discounted in favor of a view that he had only a cut lip and a little bruising.