Tarja Soile Susanna Turunen-Cabuli (born August 17, 1977), generally known as Tarja Turunen or simply Tarja, is a Finnish singer-songwriter. She is a soprano and has a vocal range of three octaves.

Turunen studied singing at Sibelius Academy and Hochschule für Musik Karlsruhe. She is well known as a professional classical lied singer but best known as the former lead vocalist of the Finnish symphonic metal band Nightwish, which she founded with Tuomas Holopainen and Emppu Vuorinen in 1996. Their combination of hard and fast guitar riffs with Turunen's dramatic, "operatic" lead vocals quickly achieved critical and commercial popularity. Their symphonic metal style, soon dubbed "opera metal", inspired many other metal bands and performers.

Turunen was dismissed from the band on October 21, 2005 (just after the performance of the band's End of an Era concert) for personal reasons. She started her solo career in 2006 with the release of a Christmas album called Henkäys ikuisuudesta. In 2007, Turunen released My Winter Storm, an album featuring various styles including symphonic metal, and started the Storm World Tour. Turunen released her third album, What Lies Beneath, in 2010. She performed several concerts in Europe, playing in metal festivals including the Graspop Metal Meeting and the Wacken Open Air, before starting the What Lies Beneath World Tour, which lasted until April 8, 2012. Her first live DVD Act I was filmed during this tour on March 30 and 31, 2012 in Rosario, Argentina. Act I was released on August 24, 2012. Turunen started the Colours in the Dark World Tour on October 17, 2013 to promote her new album Colours in the Dark. Her second live DVD was filmed during the events of Beauty and the Beat and was released on May 30.