Achilles Morris (May 8, 1800 – February 15, 1847) was an American politician and military officer who served as Abraham Lincoln's commanding officer in 1832 during the Black Hawk War and defeated Lincoln in the Illinois House of Representatives election for Sangamon County the same year. Seven years later in 1839 Morris served as the Vice President of the Democratic-Republican Party of Illinois, and in 1840, Lincoln authored a bill for an Act to Establish a State Road from Petersburg in Menard County to Waverly in Morgan County where he appointed Achilles Morris as Commissioner. Morris later served alongside Lincoln at the Railroad Convention in 1845. The chairman of the convention was Samuel H. Treat, and the delegates elected were Nathaniel Pope, David J. Baker, John J. Hardin, Josiah Lamborn, Thomas Lewis, Abraham Lincoln, and Achilles Morris. Morris was a Jacksonian democrat.

In 1846, Achilles Morris returned to military service to lead a volunteer company from Sangamon County in the Mexican American War. He died in Mexico from disease on February 15, 1847, and was buried with full military honors.

Achilles Morris was born in Kanawha County, Virginia in present-day Marmet, West Virginia to Benjamin Morris (born 1770), a veteran of the Northwest Indian Wars. The Morris family in Kanawha County were the first permanent European-Colonial settlers in the region beginning in 1773. Morris's uncles included Justice and Sheriff Leonard Morris a former Virginia spy under George Washington, Virginia State House representative William Morris Jr, Capt. John Morris the commander of Kanawha County's ranger company, Joshua Morris, and Henry Morris.

Morris's cousins included US Representative Calvary Morris, Bishop Thomas Asbury Morris, Virginia state representative Edmund Morris, Indiana Lt. Governor Major Gen. Milton Stapp, Colonel James T. B. Stapp who was nominated by President Zachary Taylor and served as the Receiver of Monies for the Land Office of Vandalia, and Capt. Wyatt Berry Stapp who Wyatt Earp was named after.

Achilles Morris's grandparents were William Morris, and Elizabeth "Eliza" Stapp Morris. Eliza was the daughter of a prominent tobacco planter Joshua Stapp. William. He was born in England in 1722, worked alongside George Hume in Orange County, Virginia, who Washington served under as deputy surveyor in 1748. William later served as a Lieutenant in the French and Indian War, and purchased a tract of land in Culpeper, Virginia in the 1750s from Hume that bordered House of Burgesses member, Henry Field. William's land was originally granted to Alexander Spotswood until his death.

In 1822, Morris married his cousin Leah Jarrett and initially moved to Cabell County, Virginia. Four years later, in 1826, he relocated his family to Sangamon County, Illinois alongside his wife's family, Jonathan Jarrett and others, joining his cousins James T. B. Stapp and Wyatt Berry Stapp who had taken up residence a few years earlier. The move to Illinois coincided with the death of his grandfather, James Jarrett. Jarrett owned the Salt mine on the Burning Springs tract, which George Washington attempted unsuccessfully to secure the rights to. Jarrett's Salt mine was sold for $12,500 and directed the proceeds be distributed among his 18 heirs for the purpose of purchasing land out west.

In 1827, Morris commissioned as a 2nd Lieutenant in the US Indian Wars in Illinois's Mounted Riflemen Regiment during the Winnebago War.

In 1831, Morris was promoted to Captain, and he commanded a volunteer company from Sangamon County in the Sauk and Fox War (Sac and Fox), which led to the Black Hawk War. The governor, John Reynolds, called up a volunteer force to "repel the invasion of the British Band". The troops marched to the Black Hawks's village on June 25, 1831. Five days later, the Black Hawks signed a treaty stating that they would not return to the east side of the river except by express permission of the government. Captain Morris was present during the signing of the treaty.