Adelbert Ames (October 31, 1835 – April 13, 1933) was an American sailor, soldier, businessman and politician who served with distinction as a Union Army general during the American Civil War. A Radical Republican, he was a military governor, U.S. Senator, and civilian governor in Reconstruction-era Mississippi. In 1898, he served as a United States Army general during the Spanish–American War. He was the last Republican to serve as the state governor of Mississippi until the election of Kirk Fordice, who took office in January 1992, 116 years after Ames vacated the office.

A staunch supporter of political equality for African Americans, Ames's tenure as governor of Mississippi was a longstanding point of controversy in the historiography around Reconstruction, with Dunning School and other "Lost Cause" historians casting him as a villain in American history. Conversely, his cause was championed by Black historians and, from the 1950s onward, other neo-abolitionist writers.

Ames was the penultimate surviving general officer of the Civil War, dying at the age of 97 in 1933. He was outlived only by Aaron Daggett, who died in 1938 at the age of 100. However, because Daggett was a brevet rank brigadier general of volunteers, Ames was the last surviving Civil War general who had held his rank in the regular U.S. or Confederate States army and was also the last surviving general of the conflict who had begun his career in the regular U.S. Army.

Adelbert (/əˈdɛlbərt/ ə-DEL-bərt) Ames was born in 1835 in the town of Rockland (then known as East Thomaston), located in Knox County, Maine. He was the younger of two sons of Martha Bradbury Ames and Jesse Ames, a sea captain who later purchased what became the Ames Mill (renowned as the producers of Malt-O-Meal) in Northfield, Minnesota. Adelbert Ames also grew up to be a sailor and became a mate on a clipper ship, and he also served briefly as a merchant seaman on his father's ship.

On July 1, 1856, he entered the United States Military Academy at West Point, New York; he graduated five years later in May 1861, fifth in his class of forty-five. Two classes had graduated that year due to the beginning of the Civil War in April. Ames' class had graduated about a month earlier than usual, while a second class, set to graduate in 1862, graduated on June 24, 1861.

Ames was then commissioned a second lieutenant in the 2nd U.S. Artillery. Eight days later, he was promoted to first lieutenant and was assigned to the 5th U.S. Artillery. During the Battle of First Bull Run that July, Ames was seriously wounded in the right thigh but refused to leave his guns. He was brevetted to the rank of major on July 21 for his actions at Manassas. In 1893, Ames received the Medal of Honor for his performance there.

Returning to duty the following spring, Ames was part of the defenses of Washington, D.C. He then fought in the Peninsula Campaign and saw action at the Battle of Yorktown from April 5 to May 4, the Battle of Gaines' Mill on June 27, and the Battle of Malvern Hill that July. Ames was commended for his conduct at Malvern Hill by Col. Henry J. Hunt, chief of the artillery of the Army of the Potomac, and he received a brevet promotion to lieutenant colonel on July 1.

Although Ames was becoming an excellent artillery officer, he realized that significant promotions would be available only in the infantry. He returned to Maine and politicked to receive a commission as a regimental infantry commander and was assigned to command the 20th Maine Volunteer Infantry Regiment on August 20, 1862. The 20th Maine fought in the Maryland Campaign but saw little action at the Battle of Antietam on September 17 while in a reserve capacity. During the Union defeat at the Battle of Fredericksburg that winter, Ames led his regiment in one of the last charges on December 13 against Marye's Heights. During the Chancellorsville Campaign in May 1863, Ames volunteered as an aide-de-camp to Maj. Gen. George G. Meade, commander of the V Corps.