Gwen Renée Stefani (; born October 3, 1969) is an American singer, rapper, songwriter, fashion designer and actress. She is a co-founder, lead vocalist, and the primary songwriter of the band No Doubt, whose singles include "Just a Girl", "Spiderwebs", and "Don't Speak", from their 1995 breakthrough studio album Tragic Kingdom, as well as "Hey Baby" and "It's My Life" from later albums.

During the band's hiatus, Stefani embarked on a solo pop career in 2004 by releasing her debut studio album Love. Angel. Music. Baby. Inspired by pop music from the 1980s, the album was a critical and commercial success. It spawned six singles, including "What You Waiting For?", "Rich Girl", "Hollaback Girl", and "Cool". "Hollaback Girl" reached number one on the Billboard Hot 100 chart while also becoming the first US download to sell one million copies. In 2006, Stefani released her second studio album, The Sweet Escape. Among the singles were "Wind It Up" and "The Sweet Escape", the latter of which was number three on the Billboard Hot 100 year-end chart of 2007. Her third solo album, This Is What the Truth Feels Like (2016), was her first solo album to reach number one on the Billboard 200 chart. Her fourth solo album and first full-length Christmas album, You Make It Feel Like Christmas, was released in 2017 and charted 19 tracks on Billboard's Holiday Digital Song Sales component chart in the United States. Stefani has released several singles with Blake Shelton, including "Nobody but You" (2020), which reached number 18 in the US.

Stefani has won three Grammy Awards. As a solo artist, she has received an American Music Award, Brit Award, World Music Award, and two Billboard Music Awards. In 2003, she debuted her clothing line L.A.M.B. and expanded her collection with the 2005 Harajuku Lovers line, inspired by Japanese culture and fashion. Billboard magazine ranked Stefani the 54th most successful artist and 37th most successful Hot 100 artist of the 2000–2009 decade. VH1 ranked her 13th on their "100 Greatest Women in Music" list in 2012. Including her work with No Doubt, Stefani has sold more than 30 million albums worldwide.