The following list represents the complete set of composers in my music collection -though, of course, it's not a complete and definitive list of every composer who has ever lived! Each name is hyper-linked to a page dedicated to describing the particular composer and why they're in my collection. At the last count, there are 574 of them, so you'll understand if most linked pages don't contain complete and polished articles as yet. Give me time!
Whilst not a definitive list of composers, you should nevertheless regard this list as 'prescriptive': that is, it shows how you should spell their names when tagging your own music CDs, even if people like Wikipedia or Last.fm beg to differ. Where appropriate, I explain the reasoning behind the choice of spelling. In most cases, it's going to be because the New Grove Dictionary of Music and Musicians begs to have the final word on the subject...