Les Rois Fainéants (the cipher or puppet kings). Clovis II. and his ten successors were the puppet kings of the Palace Mayors. Louis V. (last of the Carlovingian dynasty) received the same designation.
“ `My signet you shall command with all my heart, madam,' said Earl
Philip. ... `I am, you know, a complete Roy Fainéant, and never
once interfered wth my Maire du Palais in her proceedings.' ” —
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Faineant from Fact Monster: