Illustration, character design
"The Duck Man is a beggar in Ankh-Morpork, who unlike Foul Ole Ron, talks like an intellectual. He is the most coherent of the Canting Crew; he can estimate how much food can be bought with a certain amount of money. It is possible that someone who sits down blindfolded with the Duck Man at the same table can carry out a normal conversation on a non-personal and non-controversial topic without finding out that the Duck Man is a beggar (no longer in the Beggars' Guild) who is considered insane.
The reason that the Duck Man is called the Duck Man, and considered insane, is that there is forever a duck sitting on top of his head, though he insists that there is not. Other small clues such as that he cannot recall his past will not be observed except in an extensive conversation. Confused memories of a time before he became the Duck Man occasionally arise, but are soon disregarded. The Duck Man is quite happy as he is."
Duckman belongs to T.Pratchett