Christina María Aguilera ( AG-il-AIR-ə, Spanish: [kɾisˈtina maˈɾi.a aɣiˈleɾa]; born December 18, 1980) is an American singer, songwriter, actress, and television personality. Known for her four-octave vocal range and ability to sustain high notes, she has been referred to as the "Voice of a Generation". Her works, which incorporate feminism, sexuality, and domestic violence, have generated both critical praise and controversy, for which she is often cited as an influence by other artists.

After appearing in several television programs as a child, Aguilera rose to prominence in 1999 with the release of her debut album, Christina Aguilera, through RCA Records. The album spawned 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)" — and earned her the Grammy Award for Best New Artist. The album's musical direction is credited with influencing the revival of teen pop in the late 1990s and early 2000s, while its Spanish-language follow up, Mi Reflejo (2000), is noted for contributing to the 2000s Latin pop boom. Displeased with the nature of her earlier work, Aguilera assumed artistic control of her fourth studio album, Stripped (2002). The music video for the album's lead single "Dirrty" sparked controversy for exploring her sexuality, leading to the departure of her teen idol image. However, further singles "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 met with favorable reviews and became the second of her career to debut atop of the Billboard 200. Its singles "Ain't No Other Man", "Candyman" and "Hurt" reached the top-ten positions in most countries. In 2010, Aguilera starred in Burlesque and contributed to its soundtrack. In subsequent years, she featured on the successful singles "Feel This Moment", "Say Something", and "Moves Like Jagger". The latter reached number one on the Billboard Hot 100 making Aguilera one of the few artists to reach the top spot over three decades. Outside of her music, she was named a spokesperson for the World Food Program (WFP), served as a coach on reality competition show The Voice (2011–2016), and acted in the drama series Nashville (2015).

Aguilera is considered a pop culture icon and is generally described as a triple threat entertainer. With estimated sales over 90 million records, she is recognized as one of the world's best-selling music artists. In 2009, she was classified as the twentieth most successful artist of the 2000s by Billboard. Throughout her career, she has accumulated numerous awards and accolades, including five Grammy Awards, two Latin Grammy Awards, two MTV Video Music Awards (VMA), one Billboard Music Award, one Guinness World Record, a star on the Hollywood Walk of Fame, and was named a Disney Legend. Aguilera is regarded as one of the most influential Latin artists in the entertainment industry; in 2013, Time listed her among the 100 most influential people in the world, and was ranked as the eighth greatest woman in music by VH1. Furthermore, she has been deemed one of the greatest singers in contemporary pop music, ranked among the greatest of all time by magazines such as Rolling Stone and Consequence of Sound.