The most famous Chinese you've never heard of?

Zeng Guofan is, according to Stephen Platt, "one of the most popular figures in China today, with dozens of books on his life and letters readily available in any airport bookstore."

Zeng was a "scholar-general" instrumental in quashing the Taiping Rebellion, which is the subject of Platt's book, and possibly the worst thing anyone did in the 19th century.