UNSEEN TERROR featured a pre-NAPALM DEATH bassist Shane Embury. Vocalist / bassist Mitch Dickinson was also in parallel a member of both HERESY and ANTICHRIST. Both Embury and Dickinson are also erstwhile members of pioneering early eighties Shropshire death Metal act WARHAMMER. In 1987 UNSEEN TERROR had two songs included on the Bailey Brothers compilation album 'Diminished Responsibility' and subsequently scored a label deal with the fledgling Earache label. The album, 'Human Error', was recorded at Rich Bitch Studios in Birmingham during September of 1987. By this stage Embury was already gigging as a member of NAPALM DEATH and, as a further side concern alongside guitarist Pete Giles and former WARHAMMER man Wayne Ashton had founded Death Metal act AZAGTHOTH, putting in one gig in London in December of that year. The band altered its formation upon completion of the record, switching Giles to bass and Dickinson to guitar. Subsequently, DOOM, EXTREME NOIZE TERROR and NAPALM DEATH drummer Mick Harris was announced as the band's new singer. In March of 1988 UNSEEN TERROR cut tracks for airing on John Peel's Radio One show and performed a solitary show in Nottingham that same month with Wayne Aston temping on bass. This line up, and the band, soon collapsed.

The 2001 CD re-issue of 'Human Error' added six extra demo tracks. Pete Giles subsequently re-surfaced in HARMONY AS ONE and SCALPLOCK. In 2004 Californian gore Metal band EXHUMED revealed they had included a rendition of the UNSEEN TERROR song 'Uninformed' on their covers album entitled 'Regurgitated Requiems: Garbage Daze Re-Regurgitated'. Japanese Grind outfit WORLD DOWNFALL paid homage that same year with a take on 'Death Sentence Of The Innocent' included on their EP 'Show Your Colors Vol. 3'.