The BCW contains short biographies of musicians, organized in two sections.
Performers of J.S. Bach's works (11,638): http://www.bach-cantatas.com/Bio/index.htm
This section contains short biographies of every performer who has taken part in a recording of Bach's vocal works: mainly singers, conductors, chorus masters, choral and instrumental groups, as well as performers of Bach's solo keyboard and lute works. You can find in this section bios of many other instrumentalists, but at this stage the collection of their bios is far from being comprehensive.
Poets & Composers associated with J.S. Bach (1,398): http://www.bach-cantatas.com/Lib/index.htm
This section contains short biographies of Hymn-writers, Librettists, Composers of Chorale Melodies (CM), Composers who used CM used by Bach, Arrangers of Bach's works for piano and for orchestra, Members of Bach Family, Thomaskantors, Bach's Pupils, Composers whose works were performed by Bach; Composers whose works were attributed to Bach, etc.
The combined number of musician bios in both sections has just crossed the number 13,000. I believe this is one of the biggest collections of its kind on the web.
If you would like to contribute a musician biography to the BCW or expand/correct existing bio, please send it to me in accordance with the guidelines at: http://www.bach-cantatas.com/Bio/IndexBio-Exp.htm