Aqua is a Danish-Norwegian Europop band, best known for their 1997 single "Barbie Girl". The group formed in 1995 in Copenhagen and achieved international success around the globe in the late 1990s and early 2000s. The band released three albums: Aquarium in 1997, Aquarius in 2000 and Megalomania in 2011. The group sold an estimated 33 million albums and singles, making them the most profitable Danish band ever.

The group managed to top the UK Singles Chart with three of their singles. The group also caused controversy with the double entendres in their "Barbie Girl" single, with Mattel filing a lawsuit against the group. The lawsuit was finally dismissed by a judge in 2002, who ruled "The parties are advised to chill".

The band's members are vocalists René Dif and Lene Nystrøm, keyboardist Søren Rasted, and guitarist Claus Norreen. During their split, Nystrøm, Dif and Rasted all achieved solo chart success, while Norreen remixed other artists' material. At a press event on October 26, 2007, the group announced a reunion tour, as well as the release of a compilation album featuring new material. Their third album, Megalomania, was released on 3 October 2011.