HYDRA is a Stockholm Black Metal band, self-styled as "grim hellenic pagan metal", was forged during 1995, originally as a solo idea of NATTFROSSA guitarist Titan (a.k.a. A. Xanthopoulos). The act was strengthened to full band status but then went into hiatus. In 1999 HYDRA was re-activated when NOCTURNAL DAMNATION singer Erebus and guitarist / bassist Flame, of NATTFROSSA, enrolled. With Tornado on drums HYRDA crafted four demo sessions 'Polemos' issued in 1999, 'Cursed Battlegrounds' in 2000, 'To Aima Emon' and 'Tantalus'. Erebus, under his real name of Dennis, forged MALEDICTUM in alliance with Marcus Ehlin, of DEVLIN and SIEBENBÜRGEN, in 2000.

The group morphed again in 2002, introducing Maugrim, of VARGAGRAV, on bass and Karl Thunder on drums. Allying with UNHOLY ARCHANGEL the group cut tracks for a split offering released via Off-Beat Records. However, this was never released. Early 2003 HYDRA signed a deal with Portuguese label Heretic Sound for a full-length album 'Phaedra'. The group's debut concert appearance, held in mid 2004 at the Tantogården in Stockholm, was captured on tape for a live demo 'Tantalus Reincarnated'. A further demo, 'Head Of Medusa', was released in December 2004.

Anders Erikksson of HYDRA featured as backing vocalist on THE PROJECT HATE's 2005 album 'Armageddon March Eternal (Symphonies Of Slit Wrists)'.