Jackson wrote:As much as I know, they were Haydn, Mozart, Beethoven, Clementi, and maybe Handel? And Khulau? Who else?
Handel was rather Baroque in my opinion.. but I'm sorry I'll try not to let my answer be subjective!
A few others are Gluck, C.P.E. and J.C. Bach, Salieri and Cimarosa. However, I must admit that the Classical era is one where not a lot composers (other than the really well-known ones) come to mind. Much unlike the romantic era where tons spring to mind.