Popplewick
From Tardis Wiki, the free Doctor Who reference
Mr Popplewick was the identity used by the Valeyard while in the Matrix, in which he claimed to be an assistant to "Mr J.J. Chambers". Popplewick was held hostage by Sabalom Glitz and his true identity was revealed by the Sixth Doctor who pulled off his mask. He declared that he knew as the performance was too perfect. (DW: The Ultimate Foe)