Bloodbath was formed in 1999 by Opeth vocalist Mikael Åkerfeldt. The band was formed to pay homage to "old school" death metal.
Original members are: Martin Axenrot (Witchery), Anders Nyström (Katatonia), Dan Swano (Edge of Sanity) & Jonas Renske (Katatonia).
Åkerfeldt left the group about a year after Bloodbath's first full length album, "Resurrection Through Carnage" because he wanted to stay more focused on his main band, Opeth. Peter Tägtgren (Hypocrisy,Pain) replaced him, and Bloodbath recorded "Nightmares Made Flesh". Tägtgren left in Feb. 2005 due to "scheduling conflicts". That same year, Åkerfeldt rejoined the band for a single live show at Germany's Wacken Open Air on August 5. Prior to the show, the band commented on the Wacken show: "Not only the first, but also the last gig for Bloodbath (with Mikael Åkerfeldt on vocals)"; later it also turned out to be the last one with Swanö. In September 2005, Bloodbath started searching for a new lead singer.
In August 2006, the band announced the departure of Swanö from their ranks due to musical differences, as well as Swanö's being busy with other projects. They simultaneously closed the vocal auditions, announcing that no suitable singer had been found.
On March 27, 2007 the band announced that a new line-up would shortly be unveiled, along with news that they were producing new material, to be released on a mini-CD towards the end of summer.
In August 2007, Renkse wrote a message on the band's official discussion forum which suggested that work was in progress.
On January 30, 2008, it was announced via the Bloodbath website that Åkerfeldt would be rejoining the line-up on vocals, along with new member Per Eriksson (ex-21 Lucifers, ex-Genocrush Ferox) on guitar.
In March 2008, the EP Unblessing the Purity was released. Also released in 2008 was the Wacken live CD/DVD The Wacken Carnage. Bloodbath released their third full length album, The Fathomless Mastery, in October 2008.
On April 25, 2011, Bloodbath released their second DVD, Bloodbath Over Bloodstock, which contains their performance at Bloodstock Festival 2010, as well as their 2008 performance at Party San.
On November 1, 2011, during the final show of the American Opeth/Katatonia tour at Ram's Head Live in Baltimore, MD, Bloodbath performed a surprise encore after Opeth's set.
On April 14, 2012, Nyström announced that Åkerfeldt officially left the group, due to lack of interest in the death metal scene.