It is sometimes claimed (inaccurately) that more books have been written
about RW than anyone who has ever lived, with the exceptions of Jesus
Christ and Napoleon Buonaparte. In fact there have been thousands of books
and many thousands of articles published about RW and his works, ranging 
from the scholarly to the totally wacko. 

A selection of the biographies of Richard and Cosima Wagner can be found
in the Wagner Books FAQ, Section II.