Paul Würdig (born 30 November 1980), better known as Sido, is a German rapper. He interprets his artist name as "super-intelligentes Drogenopfer" (super-intelligent drug victim). It used to stand for "Scheiße in dein Ohr" (shit in your ear), a line from his track Terroarr. Sido is currently signed to Urban/Universal Music Group.

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.

Würdig's career began in 1997, as one half of duo Royal TS (now A.i.d.S) with B-Tight, both of whom were later signed to the label Berlin hip hop Royal Bunker and then to Aggro Berlin in 2001. As of 2009 Sido is signed to Universal Music Group.