Wilson Marion Cooper (December 17, 1850 – July 17, 1916) of Dothan, Alabama, was a notable musician and music teacher within the Sacred Harp tradition.
Perhaps the most significant contribution of his book was adding alto parts to the songs, the majority of which were originally written with three vocal lines (treble, tenor, bass).
In 1914, a judge found in favor of James, concluding, "An alto may be an improvement to a song to some extent, and probably is; but it can hardly be said to be an original composition, at least in the sense of the copyright law....
Cooper's added alto parts in the style and texture of White and King's Sacred Harp reveal a knowledge of and loyalty to the tradition.
Recent research has revealed that a few songs were added to the book between 1909 and 1927. Cooper also edited a monthly musical periodical, Zion Songster, at Dothan in the early part of the 20th century.
W. M. Cooper died in Palm Beach, Florida and is buried in the Dothan City Cemetery in Houston County, Alabama.