There are currently 9 known artists/groups with this name. 1: Turkmen rock band (Turkmenistan), playing both group's own creations as well as native and foreign popular music stuff (covers). 2: Japanese indie rock band. 3: Swedish "Dansband" group started 1990.
Their official site is http://www.blackjack.se (currently only in Swedish language) 4: Rapper from France. 5: Belgian hardrock cover band. 6: Italian rock band.