Christina María Aguilera (born December 18, 1980) is an American pop singer and songwriter. Aguilera first appeared on national television in 1990 as a contestant on the Star Search program, and went on to star in Disney Channel's television series The New Mickey Mouse Club from 1993–1994. Aguilera signed to RCA Records after recording "Reflection" for the film Mulan. She came to prominence following her debut album Christina Aguilera (1999), which was a commercial success spawning three number one singles on the Billboard Hot 100. A Latin pop album, Mi Reflejo (2001), and several collaborations followed which garnered Aguilera worldwide success, though she was displeased with her lack of input in her music and image.

After parting from her management, Aguilera took creative control over her second studio album, Stripped (2002), which although received mixed reviews – was popular with the public, and thus produced substantial sales. The second single, "Beautiful", was a commercial success and sustained the album's sales amidst controversy over Aguilera's provocative image. Aguilera's third studio album, Back to Basics (2006), included elements of soul, jazz, and blues music, and was released to positive critical reception. Aguilera's fourth studio album Bionic will be released in June 2010.

Aside from being known for her vocal ability, music videos and image, musically, she includes themes of dealing with public scrutiny, her childhood, and female empowerment in her music. Apart from her work in music, she has also dedicated much of her time as a philanthropist for charities, human rights and world issues. Aguilera's work has earned her numerous awards, including four Grammy Awards and a Latin Grammy Award, amongst fifteen and three nominations respectively. Rolling Stone ranked her number fifty-three on their list of the Best 100 Singers of All-Time list, ranking as the youngest and only artist on the list under the age of thirty. She has become one of the most successful recording artists of the decade, selling more than 43 million records worldwide

Aguilera who is a soprano, has rivaled many of her other contemporaries and has been referred to as the "voice of her generation" and a blue eyed soul singer. In the MTV special All Eyes on Christina, John Norris said that Aguilera "has a four-octave vocal range". Aguilera also topped COVE's list of the 100 Best Pop Vocalists with a score of 50/50 and came fifth in MTV's 22 Greatest Voices in Music. Aguilera has also been known to sing in the high whistle register, high Belt (she can belt to high F ( F5)). A review in an Entertainment Weekly article mentions her "tackling that dog-whistle high note" at the 3:20 mark in the song "Soar" from her album Stripped.[88] Her rendition of "It's A Man's Man's Man's World" at the 49th Grammy Awards ranked third in the Grammy's Greatest Moments List behind Celine Dion's performance of "My Heart Will Go On" and Green Day's performance of "American Idiot". In an interview, Dion described Aguilera as "probably the best vocalist in the world." During the work on Back to Basics, DJ Premier explained, "She really represents true music and true singing. She can belt out notes. She has true lungs." Rolling Stone ranked Aguilera at 58 on their list of the 100 Greatest Singers of All Time, the youngest singer on the list.

Since her debut in 1999 Aguilera has been compared to the likes of Mariah Carey and Whitney Houston. A review in the Los Angeles Times compared Aguilera's vocal stylings to Barbra Streisand, Gladys Knight, and Aretha Franklin adding, "Aguilera's Streisand-esque tendencies are a good thing; they're helping her figure out how to become the "great singer" she's been dubbed since she released her first single, the wise-beyond-its-years "Genie in a Bottle", at 18." Although praised for her vocals, Aguilera has been labeled for oversinging in her songs and concerts. Longtime producer and writer, Linda Perry, commented on working on the record, "Beautiful", saying, "I tried to keep it straight. I told her to get rid of the finger waves. Every time she'd start going into "hoo-ha", I'd stop the tape. I'm like, 'You're doing it again.'" Perry ended up using the first take saying, "She had a hard time accepting that as the final track. It's not a perfect vocal – it's very raw. She knows her voice really well, and she knows what's going on. She can hear things that nobody else would catch."

One of Aguilera's major influences and idol is blues singer Etta James, whose classic song "At Last" has been covered by Aguilera throughout her career. Aguilera says, "Etta is my all-time favorite singer. I've said it for the last seven years — since I had my first debut record out - in every interview. I mean, all of Etta's old songs, countless songs I could name, I grew up listening to." The majority of her album, Back to Basics, pays tribute to James and other pop standard singers who many originated from the 1950s. In her early years she listened to vintage jazz, blues, and soul music. The album included an unreleased song, "Slow Down Baby", which sampled a Gladys Knight & the Pips song. A review in The Guardian declared, "Practically everything recorded before Aguilera was born blurs into one amorphous genre, which she categorises, somewhat inadequately, as "fun music". Aguilera has also named Madonna and Janet Jackson as two of her biggest influences "for being re-inventive and being brave as strong females, to explore whatever, even if they do get bad press. It's just like they were fearless." Her other musical influences include Aretha Franklin, Whitney Houston, and Nina Simone.

Aguilera cites the musical The Sound of Music and its lead actress, Julie Andrews as an early inspiration for singing and performing. She mentioned the "Golden age of Hollywood" as another inspiration in which she says, "I'm referencing Marlene Dietrich, Marilyn Monroe, Carole Lombard, Greta Garbo, Veronica Lake". In her music video for "Ain't No Other Man" she plays her alter ego, "Baby Jane" in reference to the film Whatever Happened to Baby Jane? The film's stars included actresses Bette Davis and Joan Crawford. The third single off Back to Basics, "Candyman" was inspired by the 1941 song, "Boogie Woogie Bugle Boy" by The Andrews Sisters which was played during World War II. She was also inspired by pin-up girls and several paintings by Alberto Vargas. Aguilera has expressed interest in cultural icons Nico, Blondie and artists Roy Lichtenstein and Andy Warhol. She has often worked with photographer and close friend, David LaChapelle who once worked with Warhol. Chapelle has shot many of Aguilera's music videos, magazine shoots and advertisements. She is also a fan of graffiti artist Banksy. In 2006 she purchased three of Banksy's works during a private art exhibition, one of them included a pornographic picture of Queen Victoria in a lesbian pose with a prostitute. Fashion has also been a part of Aguilera's music career and image which she has used as a form of expression during performances and music videos. In 2003 she became the muse and inspiration for Donatella Versace's 2003 fall line. Versace also designed pieces her tour the following year. Aguilera is also a fan of Roberto Cavalli, John Galliano, Marc Jacobs, and Alexander McQueen whose designs she has worn throughout her career.