"The Knife is a prolific electronic indie duo from Sweden formed in 1999. The band consists of siblings Karin Dreijer Andersson and Olof Dreijer, who also run their own record company, Rabid Records and were in a previous project Honey Is Cool.
One of the group's distinguishing characteristics is their unwillingness to cooperate with the media or the mainstream music scene. The group rarely makes public appearances, most of their promotional photos feature the members wearing masks, and until recently, they outright refused to perform live concerts. They use venetian masks similar to those that can be seen in the movie Eyes Wide Shut - which had its premiere the same year that The Knife was formed. Recently the group has showed themselves in public wearing masks formed as bird's beaks, similar to those used by medieval doctors."

more: http://en.wikipedia.org/wiki/The_Knife