James Cameron (March 1, 1800 – July 21, 1861) was a Pennsylvanian who served as colonel of the 79th New York Volunteer Infantry Regiment of the Union Army during the early days of the American Civil War (Civil War). He was the brother of Simon Cameron, United States Senator and first United States Secretary of War in the cabinet of President Abraham Lincoln. At the age of 61, James Cameron was killed in action at the First Battle of Bull Run, the first large battle of the war, on July 21, 1861.

James Cameron was born on March 1, 1800, in Maytown, Lancaster County, Pennsylvania. His parents were Charles Cameron and Martha Pfoutz. His older brother, Simon, was born a year earlier, on March 8, 1799. When James was eight years old, the family moved to Northumberland County, Pennsylvania, where his father died within the year at Lewisburg, Pennsylvania. His mother was left with eight children and without means of support. Simon and James thus had to make their way in the world at an early age.

On his forty-seventh birthday, Cameron has been quoted as having said he had been a cow-boy, a plough-boy, a collier, a blacksmith, a tanner, a tailor, a printer, a brewer, a contractor, an alderman, a superintendent of railroads, a lawyer, a prosecuting attorney, and an aide to the governor. At age 19, James went to work in the same print shop with his brother Simon. He became editor of the "Lycoming Gazette" in 1824 and of the "Political Sentinel" in Lancaster, Pennsylvania, in 1827. He studied law in the office of future President James Buchanan before turning to government contracting.

Cameron married a widow, the former Rebecca (Lemon) Galbraith, in 1829. He was superintendent of motive power on the Columbia Railroad in 1839. In 1843, he became deputy attorney general of the Lancaster, Pennsylvania mayor's court.

In 1847, Cameron accompanied Pennsylvania troops to the Mexican–American War as a sutler. He later became a colonel in the Pennsylvania militia. After the war, he practiced law, was superintendent of the Philadelphia and Columbia Railroad and became a farmer on a large property.

By the time the Civil War began, Cameron was in retirement at an estate on the banks of the Susquehanna River according to some sources while at least one reference states he was superintendent of the Northern Central Railway at Sunbury, Pennsylvania.

At the outset of the Civil War, James Cameron decided to serve as a matter of duty and he proceeded to Washington, D.C. The 79th New York Volunteer Infantry Regiment, known as the "Highlanders" because its initial core militia companies were composed mostly of Scotsmen or men of Scottish descent, was one of the earlier units to arrive in Washington, D.C., after President Lincoln called for troops to suppress the rebellion. Having arrived under the command of its lieutenant colonel, the 79th offered the position of colonel to James Cameron, a prominent man of Scottish descent and brother of Simon Cameron, the Secretary of War. At least two sources suggest that Simon Cameron's influence played a part in the selection. James Cameron accepted the position of colonel of the regiment on June 20, 1861. By the time the regiment had filled its ranks, a majority of the men were not of Scottish background and in fact, many were of Irish heritage.

On July 7, 1861, the 79th New York Infantry moved to Virginia as Major General Irvin McDowell began the advance of the Union Army that would lead to the First Battle of Bull Run. The regiment was in the division of Brigadier General Daniel Tyler and the brigade of Colonel William T. Sherman. On July 18, 1861, Tyler's division and the 79th New York Infantry participated in a reconnaissance in force in which the regiment came under fire and where the Union force was unable to penetrate the Confederate line at the Battle of Blackburn's Ford.