Charles Henry Parr (March 18, 1868 – June 10, 1941) was an American mechanical engineer, inventor, and pioneer in developing the gasoline-powered agricultural tractor and cofounder of the Hart-Parr Company.^[1]

Parr was born March 18, 1868, in Wisconsin, the son of Martha and John Parr. He had five siblings. He attended high school in Dodgeville, Wisconsin, before attaining a degree in mechanical engineering from the University of Wisconsin–Madison, where he met his future partner, Charles Walter Hart.^[2] Both men graduated with honors.^[3]

After graduation, while still in Madison, Parr and Harr established a small engine company. They then moved to Charles City, Iowa, where Hart was born,^[3][4] and started the Hart-Parr Company. In 1902, they developed a gasoline engine for tractors and one year later invented the first known kerosene-run engine, which needed just 50% of the fuel that ran the gasoline engine.^[4] Also 1903, they built the country's first internal combustion engine.^[3] For a time, Hart-Parr tractors were a leading type, sold in the US and other countries.^[1] During World War I, the company also made shells for the army.^[5]

Parr left the company in 1923 to work for the Street Sweeper Company in Elgin, Illinois,^[6] but returned and stayed with Hart-Parr and the successor Oliver Farm Equipment Company until he died in 1941.^[1]

He married Gertrude Gates of Beloit, Wisconsin, in August 1898. They had a son and five daughters.^[2] He served on the library and school boards and was a leader of the First Congregationalist Church. He was also an active member of the Freemasons, including high priest of the Royal Arch Masons and commander of the Knights Templar. During a family vacation to Los Angeles, California, Parr died on June 10, 1941. Gertrude died months earlier, February 17, 1941. They are buried at Riverside Cemetery, Charles City, Iowa.^[2]

His home, the Charles Henry Parr House, in Charles City, Iowa is listed on the National Register of Historic Places.^[7]