A4, A04, A.IV, A.4 or A-4 may refer to:

Whitney Elizabeth Houston (August 9, 1963 – February 11, 2012) was an American recording artist, actress, producer, and model. In 2009, the Guinness World Records cited her as the most-awarded female act of all-time. Houston was one of the world's best-selling music artists, having sold over 170 million albums, singles and videos worldwide. She released seven studio albums and three movie soundtrack albums, all of which have diamond, multi-platinum, platinum or gold certification. Houston's crossover appeal on the popular music charts, as well as her prominence on MTV, starting with her video for "How Will I Know", influenced several African American female artists to follow in her footsteps.

Houston is the only artist to chart seven consecutive No. 1 Billboard Hot 100 hits. She is the second artist behind Elton John and the only female artist to have two number-one Billboard 200 Album awards (formerly "Top Pop Album") on the Billboard magazine year-end charts. Houston's 1985 debut album Whitney Houston became the best-selling debut album by a female act at the time of its release. The album was named Rolling Stone's best album of 1986, and was ranked at number 254 on Rolling Stone's list of the 500 Greatest Albums of All Time. Her second studio album Whitney (1987) became the first album by a female artist to debut at number one on the Billboard 200 albums chart.

Daniel Barenboim, KBE (born 15 November 1942) is an Argentine-born pianist and conductor. He has served as music director of several major symphonic and operatic orchestras and made numerous recordings.

Currently, he is general music director of La Scala in Milan, the Berlin State Opera, and the Staatskapelle Berlin; he previously served as Music Director of the Chicago Symphony Orchestra and the Orchestre de Paris. Barenboim is also known for his work with the West-Eastern Divan Orchestra, a Sevilla-based orchestra of young Arab and Israeli musicians, and as an outspoken critic of the Israeli occupation of Palestinian territories.

Barenboim has received many awards and prizes, including an honorary Knight Commander of the Order of the British Empire, France's Légion d'honneur both as a Commander and Grand Officier, the German Großes Bundesverdienstkreuz and Willy Brandt Award, and, together with the Palestinian-American scholar Edward Said, Spain's Prince of Asturias Concord Award. He has won seven Grammy awards for his work and discography.