Adna Romulus Johnson (December 14, 1860 – June 11, 1938) was a teacher, lawyer, and U.S. Representative from Ohio for one term from 1909 to 1911.

Born in Sweet Springs, Missouri, Johnson moved with his mother to a farm in Lawrence County, Ohio, in 1864, where attended the common schools.

Johnson graduated from the University of Michigan Law School at Ann Arbor in 1887 and practiced his profession in Ironton, Ohio.

Johnson served as president of the Ohio State Bar Association in 1933.

This article incorporates public domain material from the Biographical Directory of the United States Congress