Wheaton, Illinois based Black Metal act NACHTMYSTIUM is centred on mentor Azentrius in studio partnership with Chris Black of SUPERCHRIST, PHARAOH and DAWNBRINGER acting as engineer and bassist. NACHTMYSTIUM was originally convened as a side venture of EZURATE member Azentrius on vocals, guitar and bass in alliance with drummer Grave of VENEFICUM. When Azentrius split away from EZURATE the NACHTMYSTIUM project became a full time venture. Later members would include ZALNIK's frontman Zmij adding session vocals to a DARKTHRONE cover version and vocalist / keyboard player Kirglord, on loan from HVELVENGEL AV HELVETE.

The band debuted with a single track demo cassette 'Holocaust Of Eternity', issued in 2000 and restricted to 200 copies. Australian label Asgard Musik published the demo 'Reign Of The Malicious' in 2001, this including a BURZUM cover version 'Lost Wisdom'.

'Unholy Terrorist Cult' followed in 2001, released by the Vinland Winds organisation. NACHTMYSTIUM debuted live during early November 2001 at the 'Unholy Devastation Festival' event in Aurora, Illinois, utilising the services of Zmij on vocals alongside Marcus Kolar from SARCOPHAGUS and FOREST OF IMPALED on bass.

The initial 2002 line-up would cite NACHTMYSTIUM as a duo of Azentrius and drummer Noctis, the latter known for his membership of both HVELVENGEL AV HELVETE or OTHENDARA. Split releases were scheduled with both KRIEG and CULT OF DAATH with a full-length album version of the earlier 'Reign Of The Malicious' demos, set for June 2002 release through Sombre Records on a vinyl format of 350 copies and Regimental Records on a CD pressing of just 600 copies.

The 2002 cassette release 'Live Onslaught' closed with a take on KRIEG's 'Black Metal ist Krieg'. The KRIEG connection was strengthened when Azentrius, acting as session bassist, recorded a series of tracks with KRIEG. The vinyl album 'Live Blitzkrieg', released by Autopsy Kitchen Records, hosted the EARTH cover track 'Charioteer - Temple Song'. Only 500 copies, pressed on swirled vinyl, were produced.

By July Noctis had been unceremoniously dumped and former studio drummer Grave re-inducted. However, the band subsequently entered the studio for fresh recordings citing a revised line up of Azentrius on lead vocals, guitars and bass, Aamonael also on lead guitars and Wargoat Obscurum of ALIOTH and CULT OF DAATH on session drums.

The eponymous 2003 mini-album included a cover version of JUDAS ISCARIOT's 'Gaze Upon Heaven In Flames'. An early 2004 release through Regimental Records, 'The First Attacks - Demos 2000-2001', combined material from the 'Holocaust Of Eternity' demo, tracks from the split demo shared with ZALNIK as well as 3 unreleased tracks.

Early 2005 saw an announcement detailing the formation of a Black Metal "supergroup" dubbed TWILIGHT, a collaboration of underground veterans seeing Azentrius joined by Wrest of LEVIATHAN, Malefic of XASTHUR, Imperial of KRIEG and Hildolf from DRAGUAR. An eponymous album, mastered by Scott Hull of PIG DESTROYER, would be recorded for the Southern Lord label.

The band partnered with GRAND BELIAL'S KEY for Scandinavian gigs in February 2006. NACHTMYSTIUM forged an unlikely touring union with PELICAN and DAUGHTERS in September. The album issued that year, 'Instinct:Decay', featured session bass from engineer Chris Black. December US shows witnessed an alliance with ZOROASTER.

The group aligned with GOATWHORE, Norwegian act 1349 and AVERSE SEFIRA for a North American tour beginning late March 2007. The band soon returned to the North American touring circuit in early May 2007, uniting with WATAIN, NEGATIVE PLANE, GRAVEWÜRM and ANGEL CORPSE for the "Antichrist Vanguard" tour.

NACHTMYSTIUM's 2008 album, 'Assassins: Black Meddle Part I', was released on 10th June via Century Media Records in North America and 23rd June through Candlelight Records in Europe. The album had been recorded during the previous December at Sanford Parker's Volume Studios and featured Tony Laureano, of DIMMU BORGIR and NILE, on drums, plus guest appearances by members of PHARAOH and YAKUZA. In May an EP, 'Worldfall', preceded the album launch. These tracks had been originally recorded for a proposed split release and featured versions of 'Rose Clouds Of Holocaust', originally by DEATH IN JUNE, and 'IV' by GOATSNAKE.

During September, NACHTMYSTIUM dropped off a North American tour featuring OPETH and HIGH ON FIRE, issuing a statement that this action was: "Due to some issues beyond our control". A second leg of the US tour started in Los Angeles on 8th October with WOLVES IN THE THRONE ROOM.

THE HAUNTED, NACHTMYSTIUM and THE AGONIST partnered for North American dates in April 2009.