Therion are a Swedish symphonic metal band led by Christofer Johnsson. Originally a death metal act, they evolved toward doom metal (with electronic and avant-garde elements) by third album Symphony Masses: Ho Drakon Ho Megas (1993). They adopted Persian modes and scales for Theli (1996), performed by a rock quintet, two classical choirs, a simulated orchestra, and an army of keyboards. Secret of the Runes (2001) was based on Norse mythology. Simultaneous releases Lemuria and Sirius B (2004) involved 171 musicians including the City of Prague Philharmonic Orchestra. Gothic Kabbalah (2007) featured five vocalists amid Therion's ambitious musical settings. Sitra Ahra (2010) melded classical aesthetics and doom metal. The three-hour rock opera Beloved Antichrist (2017) included no less than 29 vocal characters. In 2021, the band issued Leviathan, the first of a projected three-volume "sonic" retrospective consisting of all new material. Leviathan II appeared in October 2022.