Paul Würdig (born 30 November 1980), better known as Sido, is a German rapper.

Würdig distinguishes himself by using provocative and aggressive lyrics. After his breakthrough with his debut album Maske in 2004, Würdig was always seen wearing a silver skull mask. However, as stated in various interviews, since 2005 he no longer wears the mask, having handed it to his former boss Specter.