Although the band achieved prominence in their home country since the release of their first single, they did not achieve worldwide fame until the release of the album Once (2004), which spawned Nightwish video clips shown on MTV in the USA for the first time, and inclusion of their music in U.S. movie soundtracks. Their biggest U.S. hit, "Wish I Had an Angel", made it onto 2 U.S. film soundtracks, as a way to promote their first North American tour (scheduled, but then cancelled due to conflicts with vocalist's solo career). They produced 3 more singles and music videos from this album, and a final one, "Sleeping Sun", from a 2005 best-of compilation, Highest Hopes, prior to their vocalist's departure.
As of 2006, the band is searching for a replacement to vocalist Tarja Turunen, who was fired at the end of 2005. A replacement for the soprano singer has not yet been found, but the four other musicians of the band plan to find one in the course of 2006, so that a new album can be recorded at the end of 2006 and beginning of 2007, and released later that year.