Hakim Sid (born 2 July 1975), better known by his stage name Demon One, is a French rapper of Algerian origin.

Hakim Sid was born Choisy-le-Roi, Val-de-Marne of an Algerian father and a French mother started rapping at a very young age. He was friends with M.S. (Mansa Konaté). He is a founding member of Intouchable alongside Dry (real name Landry Delica).

Demon One made his first appearance with Dry, M.S. in 1994. In 1996, Intouchable became part of the rap collective Mafia K-1 Fry. In 1997, Mamad joined Intouchable.

Demon One appeared with some solo work in the second album of Ideal J Le combat continue in 1998 with the track "L'amour". In 2000, Intouchable released their debut album Les points sur les I and started a tour with rap band 113.

Demon One also released solo tracks on various Mafia K-1 Fry projects. In 2005, Intouchable released their second studio album La vie de rêve. Thanks to the track "La gagne" with Tonton David, Intouchable gained a lot of fame.

In 2007, Demon One launched "Votez pour moi" (meaning vote for me). In June 2007, he released his solo street album Mon rap with many unpublished tracks most notably "Monsieur le Maire" addressed to mayor of Choisy-le-Roi. In January 2008, he returned with a full studio album Démons et merveilles.

In November 2011, he announced his withdrawal from the Mafia K'1 Fry collective.

Demon One's biggest hit in France was the 2008 single "J'étais comme eux" featuring Soprano.