John Reily Knox

John Reily Knox (May 20, 1820–February 7, 1898) was an American attorney who was the principal founder of Beta Theta Pi Fraternity at Miami University in 1839.

Knox was born on May 20, 1820, on a farm between Millville, Ohio, and Venice, Ohio, and graduated from Miami University "first rank in his class" and president of the Union Literary Society. In Beta Theta Pi, he is referred to as "Pater" in acknowledgment of his role in the origin and design of the fraternity.

Knox taught school in Mississippi, 1841–42, and was admitted to the bar and practiced at Greenville, Ohio, 1843–52; Dayton, Ohio, 1852–56; and Greenville again 1856–98. He was a partner in the Greenville-based law firm of Knox, Martz, and Rupe. A Whig until the formation of the Republican Party, he was an Ohio Presidential Elector in 1860 and cast his vote for Abraham Lincoln. Knox was the president of Greenville Law Library, president of Darke County, Ohio Bar Association, vestryman of St. Paul's Protestant Episcopal Church, and a member of the Miami University Board of Trustees, 1869–98.

Knox was married on November 27, 1845, to Isabel S. Briggs. They had four children.

Knox died on February 7, 1898, in Darke County, Ohio. He is buried in Greenville Cemetery, Greenville, Ohio.