Johann Sebastian Bach (1685–1750) was a German composer and musician of the Late Baroque period, widely regarded as one of the greatest composers in Western music history. Born in Eisenach into a family of church musicians, Bach held several important musical positions, most notably as Thomaskantor in Leipzig from 1723 until his death, where he was responsible for music and directed the Collegium Musicum, a secular ensemble. Bach composed extensively across many genres, including organ works, cantatas, Passions, oratorios, motets, and instrumental music. His compositions, including the Brandenburg Concertos, The Well-Tempered Clavier, and the Mass in B minor, showcase intricate counterpoint and complex structures that deeply shaped Western music, and are celebrated for their intellectual depth, technical command, and artistic beauty.

A significant aspect of Bach’s oeuvre is his chorale settings; four-part harmonizations of Lutheran hymn tunes. Around 400 of these chorale harmonizations survive, mostly dating from the early 18th century. They typically feature a pre-existing hymn melody in the soprano, with harmonized alto, tenor, and bass parts in a homophonic texture, each syllable of the text set once without repetition. Many chorales appear within larger vocal works such as cantatas, motets, Passions, and oratorios, often concluding cantatas with a sublime harmonization of the chorale on which the work is based. Bach also incorporated chorales in organ compositions as chorale preludes and partitas, and sometimes elaborated hymn melodies with thorough bass accompaniment. His chorale work reached a pinnacle in the St Matthew Passion, where multiple arrangements of the chorale "O Sacred Head Now Wounded" demonstrate his mastery of chorale harmonization, blending French, German, and Italian styles to express profound spiritual emotion. Bach’s chorale settings remain central to the Lutheran musical tradition and continue to influence sacred music worldwide.