Christina María Aguilera (; Spanish: [aɣiˈleɾa]; born December 18, 1980) is an American singer, songwriter, actress, and television personality. Referred to as the "Voice of a Generation", she is credited as one of the artists responsible for reviving teen pop in the late 1990s and using her vocal ability to address such topics as sexuality, feminism, and domestic violence. She has frequently reinvented her image, becoming known for her risqué and unconventional looks. Her works have generated both critical praise and controversy in the media, with which Aguilera is often cited as an influence by other artists.

Born in New York City and raised in Pennsylvania, Aguilera began her career as a child star after appearing in various television programs during the 1990s, including The Mickey Mouse Club (1993–1994). In 1999, after signing a recording contract with RCA Records, she transitioned to pop music with her self-titled debut album, which had three Billboard Hot 100 number-one singles: "Genie in a Bottle", "What a Girl Wants", and "Come On Over Baby (All I Want Is You)", establishing her as a bubblegum pop artist. Aguilera assumed artistic control with Stripped (2002), for which she changed the course of her career; in the music video for "Dirrty", she sparked controversy for exploring her sexuality, leading to the departure of her teen idol image. However, "Beautiful", "Fighter", and "Can't Hold Us Down" became top-ten singles in many countries, and she was named the most successful female artist of 2003.

Her fifth album, Back to Basics (2006), was received with favorable reviews and became the second material of her career to debut atop of the Billboard 200. The album had the successful singles "Ain't No Other Man" and "Hurt". In 2010, Aguilera starred in the film Burlesque, which was nominated for the Golden Globe Award for Best Motion Picture – Musical or Comedy, in addition to contribute with its soundtrack. In the following years, she was featured on top-ten singles "Moves Like Jagger", "Feel This Moment", and "Say Something"; with the foremore, she reached number-one on the Billboard Hot 100 in three consecutive decades, which song also placed among the best-selling digital singles of all time. Outside of her work in the music industry, she acted as a spokesperson for the World Food Program (WFP), as well as a coach in the reality competition show The Voice (2011–16) and as an actress in the drama series Nashville (2015). In 2019, she embarked on The Xperience, her first residency at the Planet Hollywood Las Vegas.

With estimated sales around 75 million records, Aguilera is recognized as one of the world's best-selling music artists; in 2009, she was classified by Billboard as the twentieth most successful artist of the 2000s. Throughout her career, she has accumulated numerous awards and accolades, including five Grammy Awards, one Latin Grammy Award, two MTV Video Music Awards (VMA), one Billboard Music Awards, one Guinness World Record, a star on the Hollywood Walk of Fame, and was named a Disney Legend. Aguilera is often considered to be one of the greatest singers of all time by magazines such as Rolling Stone and Consequence of Sound, and was chosen the greatest of Latin origin by Latina. In 2013, Time elected her as one of the 100 most influential people in the world, while she has been listed as one of the most influential artists in the phonographic industry by VH1 and The Independent.