Paul Hartmut 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 into your ear), a line from his track "Terroarr".

Sido distinguishes himself by using provocative and aggressive lyrics. After his breakthrough with his debut album Maske in 2004, he was always seen wearing a silver skull mask. However, since 2005, he no longer wears the mask.

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 Urban/Universal Music Group.