Willis Sharpe Kilmer (October 18, 1869 – July 12, 1940) was a patent medicine manufacturer, newspaperman, horse breeder, and entrepreneur.

Continued success led them to construct the six-story Kilmer Building at Lewis and Chenango Sts in downtown Binghamton, NY as their manufacturing and business headquarters in 1903.

The Swamp Root formulation fell out of favor after the advent of the 1906 Pure Food and Drug Act, which resulted in the federal government imposing testing and labeling requirements on a variety of products, including patent medicines with dubious claims.

Medical health experts noted that it was being advertised under false pretenses, the formula was potentially dangerous and there was no evidence it could cure kidney or liver disease.

Kilmer died from pneumonia in Binghamton on July 12, 1940,[3] having amassed a fortune of some $15 million, mostly from the sale of the patent medicine Swamp Root tonic.