Edward Mordake was reportedly the 19th century heir to an English peerage. He supposedly had an extra face on the back of his head, which could neither eat nor speak, although it could laugh and cry. Edward begged doctors to have his “demon head” removed, because, supposedly, it whispered satanist language to him at night, but no doctor would attempt it. He committed suicide at the age of 23.
This is the story as told in Anomalies and Curiosities of Medicine:
He was a young man of fine attainments, a profound scholar. But upon the back of his head was another face, that of a girl, ‘lovely as a dream, hideous as a devil’. The eyes would follow the movements of the spectator, and the lips ‘would gibber without ceasing’.