There is at least 4 bands under the name Demoniac.

1.) Demoniac from Germany is the follow up band of the Death Metal band Purulent Obduction (1989-1993) that changed it's name in early 1993. They didn't change their Doom/Death Metal style until Blacksoul joined in mid 1993 and the whole song material became more Black/Death Metal influenced and much faster. In January 1994 Count Damien Nightsky and Lord Asmoday had been kicked out and later formed Andras while the remaining members continued as Moonblood after releasing the last Demoniac-demo (a kinda compilation of earlier recordings) that was recorded still together in late 1993. The band reunited in summer 2013 with the original Purulent Obduction line-up and released a full-length album, Malleus Christianitatis at Misanthropia Discos in 2016.

2.) Demoniac was a Black Metal band from New Zealand formed by Lindsay "Behemoth" Dawson, Sam "Heimdall" Totman, and Mark "Adramolech" Hamill (who also was playing in Head Like A Hole). The musical style of the band varied dramatically throughout their career. Their earlier output was mostly black metal influenced, while their later work consisted of power metal style guitars and melodies with black metal style screaming vocals. Demoniac toured Europe with acts such as Enslaved and Dark Tranquility.

Behemoth played bass in the studio, but in the band's later days they used a succession of live session players to allow him to fully focus on his vocal performance. The eventually hired Diccon Harper as a full-time bass player, but the band split before he could record anything with them. Demoniac relocated to London in 1997 due to the lack of exposure for their style of music in their home country, and in the process abandoned drummer Mark Hamill, with some acrimony. It was after this that Herman Li joined the band as second guitarist. After Demoniac split, he and Sam Totman went on to form DragonForce. Harper and drummer Matej were also briefly involved in the new band, and Behemoth performed as a guest on their "Inhuman Rampage" album.

3.) Speed/power/heavy metal from Beograd, Serbia (ex-Yugoslavia) formed in 1986. They released 5 demos and Touch The Wind LP (1992, Explosive records).

4) Blackened thrash metal band from Limache, Chile, formed in 2011. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.