Book History A to Z: R is for Roman a clef

I find this one pretty interesting--it is sort of like an "unauthorized" biography, only it goes a step further by fictionalizing those involved.  Of course, part of the reason is to prevent the author from being hauled into court, or otherwise retaliated against, but as you know that doesn't always work.  The translation is "novel with a key,"  they key presumably being knowing who is who in the book.  According to one source, the originals actually had a key--published separately, that named names. 
The Roman a clef began, according to the Encyclopedia Britannica, during the 17th century in France, when a few stout souls dared to write about courtiers of Louis XIV and include them in historical fiction.  Later examples include Simone de Beauvior's Mandarins, and the more recent Primary Colors.