::In the broader sense of the term, yes Marx did write Classical music (as opposed to Jazz or Rock etc.) in that he wrote pieces such as concerti, string quartets and orchestral works. In the stricter sense of writing music in the style of the Classical period (circa 1750-1830), only Beethoven and Mozart fit the bill. J.S. Bach wrote baroque music. (It may of course be possible that you meant C.P.E. Bach, who is counted as a classical composer - so perhaps Karl Marx is the odd one out after all.)