Dent was born in Putnam County, Illinois, the son of George Dent and Comfort (Ijams) Dent. George Dent held a number of elective offices in Putnam County, including clerk of the circuit and county courts, county judge, and member of the Illinois House of Representatives in 1853 and 1864. s Legislative Roster Thomas Dent was educated at public schools in Illinois and Ohio, and then, at age 15, became permanently employed as his father's assistant.
After studying law on his own, Dent was admitted to the bar in 1854, at which time he established a law practice in Hennepin, Illinois. He moved to Chicago in 1856, forming a legal partnership with Martin R. M. Wallace. Dent married Susan Strawn in 1857. Also in 1857, he moved to Peoria, Illinois, but was back in Chicago the next year, and in 1860 formed a partnership (Arrington & Dent) with Judge A. W. Arrington that would last until Arrington's death in 1867. At that point Dent joined forces with William P. Black to establish a new law firm, Dent & Black. Dent had a successful practice with many corporate clients, including banks, insurance companies, a railroad company, and the Chicago Board of Trade. Dent argued several cases to the Supreme Court of the United States.
An elder of the Presbyterian Church in the United States of America, Dent served as a director of the McCormick Theological Seminary for nearly 4 decades.
- 'The Chicago Bar Association Record,' June 1925, vol. 8, No. 9, In Memoriam-Thomas Dent, pg. 4-5
- 'Illinois Briefs-Death of Thomas Dent' The Monmouth Daily Review Atlas, December 26, 1924, 2
- 'Illinois Legislative Roster-1818-2017
- 'The National Cyclopedia of American Biography,' volume XVII, James T. White & Company, New York: 1920, Biographical Sketch of Thomas Ijans Dent, pg. 278
- Thomas Dent at Find a Grave
- Arba Nelson Waterman, Historical Review of Chicago and Cook County and Selected Biography (1908)
- The Handbook of Chicago Biography, ed. John J. Flinn (1893)
- Letter from Dent to his cousin Louis Ijams