Marshall Arnold (October 21, 1845 – June 12, 1913) was a U.S. Representative from Missouri.

Born at Cook Settlement, near Farmington, St. Francois County, Missouri, Arnold attended the common schools.

He was admitted to the bar in 1872 and commenced practice in Commerce, Missouri.

He served as member of the State house of representatives in 1877–1879.

He resumed the practice of law in Benton, Missouri, and died there June 12, 1913.