A Power Metal act that issued three demos, 1999's 'Seventh One', the 2000 effort 'Through Burning Skies' and 'The Celestial Prophecy' during 2001 on their way to securing a record contract. The group, based out of Hunnebostrand, was conceived in late 1997 by guitarists Christoffer Hermansson of SOUL REAPER and TEARS OF SAHARA and Johannes Losbäck of DECAMERON repute. The fledgling band would be brought up to strength with the addition of former ANGUISH and TEARS OF SAHARA vocalist Rino Fredh, ex-LOST bassist Jörgen Olsson and drummer Jonny Edvardsson. The band won a series of awards at the Swedish West coast contest 'Rock Of Bohuslän', the prize for which was a demo recording. After numerous delays these sessions surfaced in 1999.

Exposure in mainland Europe was increased with the inclusion of the demo track 'The Seventh Eye' on a cover mount CD of unsigned acts 'Unerhört' on the esteemed German Rock magazine 'Rock Hard'.

For the demo 'The Celestial Prophecy' SEVENTH ONE drafted new drummer Mats Karlsson, another erstwhile TEARS OF SAHARA veteran. Interest in Germany was high and SEVENTH ONE duly signed a development deal with METALIUM's Lars Ratz for recording. At this stage Tobias Kjellgren, a veteran of extreme Metal bands DISSECTION, DECAMERON, SWORDMASTER, SACRAMENTUM and SOUL REAPER, was pulled in on the drum stool for debut album 'Sacrifice', released through the Massacre label in October 2002.

During 2003 drummer Mats Karlsson participated in DREAMS FALL, a studio unit assembled to record a three track demo billed 'Freedom's Calling'. The group involved a quite illustrious cast, comprising singer Andy Engberg, of LION'S SHARE, SECTION A, SORCERER, BOOK OF REFLECTIONS and TWILIGHT, guitarist PONTUS NORGREN of TALISMAN, HUMANIMAL, GREAT KING RAT and JEKYLL & HYDE, bass player Chris Goldsmith, of GLORY, DAMAGE DONE and FULL STRIKE and keyboard player Tobias Marberger.

SEVENTH ONE marked a return in September of 2004 with the album 'What Should Not Be' released through Armageddon Products. In addition, the band had the track 'Crimson Sky' featured on the 'Armageddon Over Wacken' DVD. Japanese versions, on the Spiritual Beast label, added a bonus track in 'Scattered'.

Guitarist Johannes Losbäck departed in February 2005. That same month the ex-SEVENTH ONE rhythm section of bassist Jörgen Olsson and drummer Mats Karlsson announced a brand new band venture, entitled HEED, in collaboration with erstwhile LOST HORIZON members singer Daniel Heiman and guitarist Fredrik Olsson. Kellgren joined up as touring member of IN FLAMES during October 2005, as regular drummer Daniel Svensson, awaiting the birth of his second child, sat out these shows.