Stratovarius is a Finnish power metal band that formed in 1985. Since their formation, they have released fifteen studio albums, four DVDs and five live albums. In its history, the band has gone through many chaotic lineup changes, and after founding guitarist Timo Tolkki's departure in 2008, there are no founding members of the band that remain. Currently, the longest standing member is singer Timo Kotipelto, who joined in 1994.
The first incarnation of the band had the name Black Water, founded in August 1984 by singer and drummer Tuomo Lassila, guitarist Staffan Stråhlman, and bassist John Vihervä. After reforming as Stratovarius, line-up changes started to occur, including Timo Tolkki replacing Black Water member Stråhlman and taking over singing duties as well, and the band expanding to a quartet with the arrival of keyboardist Antti Ikonen the following year. Under this line-up, the band released its first album Fright Night in 1989, with Tolkki as the only songwriter. While the band went through many bassists, the band released the albums Twilight Time in 1992 and Dreamspace in 1994. In 1994, Tolkki decided to stop acting as lead vocalist, with Kotipelto joining the band. After the release of Fourth Dimension in 1995, Ikonen and the last Black Water member, Lassila, left the band and were replaced by Jens Johansson and Jörg Michael respectively.
This line-up consisting of Kotipelto, Tolkki, bassist Jari Kainulainen, Johansson and Michael, now recognized as the "classic line-up" of Stratovarius, became the longest line-up in its history (1995-2005). With this line-up, the band released eight albums including most of their popular works (releasing an album with the same line-up than its predecessor for the first time) until the release of a self-titled album in 2005, after which Kainulainen departed and was replaced by Lauri Porra. In 2008 guitarist, sole founder, composer and main lyricist Timo Tolkki, being highly critical of their last album and tired of the tensions between the members, decided to disband Stratovarius. However, at the demand of the rest of the band, he agreed to let them continue as Stratovarius while leaving the band. He subsequently regretted his decision, stating that the current band had nothing to do with Stratovarius which he considered as mainly his own work.
Despite the controversy of Tolkki's departure, the band's following albums Polaris (2009) and Elysium (2011) received positive reception, with various critics and fans considering them their best albums in the last decade. These were the first albums with Porra and new guitarist Matias Kupiainen, and all members except Michael were part of the songwriting process. After a small "Farewell Jörg" tour in Finland, Jörg Michael departed for personal reasons in 2012. With new drummer Rolf Pilve, the band released Nemesis in 2013 and Eternal in 2015.