Zadok Casey (March 7, 1796 September 4, 1862) was an American politician who served as a U.S. Representative from Illinois from 1833 to 1843. He founded the city of Mount Vernon around 1817. He was elected to the Illinois House of Representatives in 1822 and to the Illinois State Senate in 1826, and was elected the fourth Lieutenant Governor in 1830. He served in the Twenty-third United States Congress (1833) through the Twenty-seventh United States Congress (1843). He was a Jacksonian Democrat. He again served in the Illinois House from 1848 to 1852, serving as speaker in 1852, and in the State Senate from 1860 to 1862. Zadok Casey was born in Greene County, Georgia. Not much is known about his early life. One story is that, as a young man, he witnessed a murder. Because he did not wish to testify, he fled to the frontier. He died in Caseyville, Illinois at age 66, and was interred at Old Union Cemetery in Mount Vernon.