Ainsworth Rand Spofford (September 12, 1825 – August 11, 1908) was the sixth United States Librarian of Congress, serving from 1864 to 1897.

Spofford was born in Gilmanton, New Hampshire. Ill health prevented him from attending Amherst College. He instead, at age 19, moved to Cincinnati, Ohio, where he became a bookseller, publisher, and newspaper man. In 1859 he became associate editor of the Cincinnati Commercial . He was also active in Republican party politics and was a delegate to the nominating convention of John Charles Frémont in 1856.

In Washington D.C. in 1861, shortly after reporting on the Battle of Bull Run for his newspaper, he accepted the appointment of Chief Assistant Librarian from Librarian of Congress John G. Stephenson. After Stephenson's resignation, President Abraham Lincoln appointed Spofford to the post of Librarian of Congress.

Spofford is generally credited with overseeing the expansion of the Library from a Congressional resource into a national institution. During Spofford's tenure, the Library expanded from over 60,000 items to more than one million. Spofford presided over the move of the Library from the Congressional Reading Room in the US Capitol to its own building, now called the Thomas Jefferson Building, in 1897, a building which Spofford campaigned for. Spofford stepped aside in favor of a younger administrator, John Russell Young, and returned to his old post of Chief Assistant Librarian, where he remained until his death.

He was a prolific author and editor and his publications include A Book for All Readers (3d ed. 1909), The Library of Choice Literature (10 vol., 1888), and the annual American Almanac (1878-89).