Opeth is a Swedish progressive metal band from Stockholm, formed in 1990. The band incorporates folk, blues, classical, and jazz elements into its usually lengthy compositions, as well as strong influences from death metal, especially in their early works. Songs may include acoustic guitar passages, Mellotrons, death growls, and strong dynamic shifts.

The group have been through several personnel changes since early in their history, including the replacement of every original member. Lead vocalist, guitarist and primary songwriter Mikael Åkerfeldt has been Opeth's driving force since the departure of founder and lead vocalist David Isberg in 1992. The band rarely made live appearances supporting their first four albums, but since their first world tour in support of the 2001 album Blackwater Park, they have performed several other major world tours.

Opeth have released fourteen studio albums, four live DVDs, four live albums (three that are in conjunction with DVDs), and two boxsets. The band released its debut album Orchid in 1995. With their eighth studio album, Ghost Reveries (2005), the band achieved chart success in several dozen countries, including Top Ten in Sweden. Their ninth studio album, Watershed (2008), topped the Finnish albums chart in its first week of release, and reached 23 on the US Billboard 200 chart. As of November 2009, the band have sold over 1.5 million copies of their albums and DVDs worldwide, including 300,000 collective SoundScans of their albums Blackwater Park, Damnation, and Deliverance in the United States. Their 14th studio album The Last Will and Testament (2024) won the Swedish Grammis award for the Best Hard Rock/Metal category.