William Walker was an American Baptist song leader, shape note "singing master", and compiler of four shape note tunebooks, most notable of which are the influential The Southern Harmony and The Christian Harmony, which has been in continuous use.

Shape notes are a musical notation designed to facilitate congregational and social singing. The notation, introduced in late 18th century England, became a popular teaching device in American singing schools. Shapes were added to the noteheads in written music to help singers find pitches within major and minor scales without the use of more complex information found in key signatures on the staff.