"Ex-Girlfriend" is a song by American ska band No Doubt from their fourth studio album, Return of Saturn (2000). The song was released as the album's lead single in early 2000 and was moderately successful, reaching the top 40 in most countries it charted in, including peaking within the top 10 in Australia, Iceland, and Spain. A review from Billboard magazine called Stefani's vocal performance on the song "fantastic".

No Doubt is an American rock band from Anaheim, California, formed in 1986. For most of its career, the band has consisted of vocalist and founding member Gwen Stefani, guitarist Tom Dumont, bassist Tony Kanal and drummer Adrian Young. Keyboardist Eric Stefani, Gwen's brother, was also a former member when the band started to release albums in 1992. Since the mid-1990s, trombonist Gabrial McNair and trumpeter Stephen Bradley have performed with the band as session and touring musicians.