There is more than one artist with this name:

1) Therion, formerly known as Blitzkrieg (1987-1988) and Megatherion (1988), is a symphonic metal band founded by Christofer Johnsson in Upplands Väsby, Sweden in 1987. In April 2008, Christofer stated that the musicians are parting in their own ways, however the band has not officially disbanded, Christofer is currently looking for new band members to continue the musical work.

Therion was initially a death metal band, however starting with 1995’s Lepaca Kliffoth, Therion began to gradually incorporate symphonic elements into their metal music. The band has seen many changes in line-up and style throughout its history. Only Christofer Johnsson, Kristian Niemann (guitars), Johan Niemann (bass), and Petter Karlsson (drums) were considered the constant members. All others, including vocalists like Sarah Jezebel Deva, Piotr Wawrzenuk, and Mats Levén, are session members.

Beginning as a death metal band, they later turned to combining orchestral elements with their metal music, employing heavy use of choirs and classical musicians, not only as additions to but also as integral parts of the composition. The band is one of the first both commercial and audience successful heavy metal with fully live orchestra featured. It is also one of the bands which originated, popularized and highly influenced the symphonic metal genre.

Therion takes its lyrical themes from various mythologies, occult and magical teachings, and ancient traditions and writings. The majority of the lyrics are written by Thomas Karlsson, head and founder of the magical order Dragon Rouge, of which Johnsson is a member. The band’s name originates from the Greek word therion (θηρίον), which means beast, in reference to the “beast” of the Christian Book of Revelation, though the word itself is taken from the Celtic Frost album To Mega Therion.

Official site: www.megatherion.com


2) Therion is a thrash metal band from United Kingdom. They released one demo during the 80's.