 Opeth is a Swedish heavy metal band from Stockholm , formed in 1990 . The group has been through several personnel changes , but singer , guitarist and songwriter Mikael Åkerfeldt has remained Opeth 's only founding member and primary driving force throughout the years . Opeth has consistently incorporated progressive , folk , blues , classical and jazz influences into their usually lengthy compositions , as well as strong influences from death metal , especially in their early works . Many songs include acoustic guitar passages and strong dynamic shifts , as well as both death growls and clean vocals . Opeth is also well @-@ known for their incorporation of Mellotrons in their work . Opeth rarely made live appearances supporting their first four albums ; but since conducting their first world tour after the 2001 release of Blackwater Park , they have led several major world tours . 
