Billy Joel (born William Martin Joel; May 9, 1949) is an American rock musician, singer-songwriter, and classical composer. Since releasing his first hit song, "Piano Man", in 1973, Joel has become the sixth best-selling recording artist in the United States, according to the RIAA.

Joel had Top 10 hits in the 1970s, 1980s, and 1990s and has 33 Top 40 hits in the United States, all of which he wrote singlehandedly. He is also a five-time Grammy Award winner, a 23-time Grammy nominee and has sold over 100 million records worldwide. He was inducted into the Songwriter's Hall of Fame (1992), the Rock and Roll Hall of Fame (1999), and the Long Island Music Hall of Fame (2006). Joel "retired" from recording pop music in 1993 but continues to tour (sometimes with Elton John). In 2001, he released Fantasies & Delusions, a CD of classical compositions for piano. In 2007, he briefly returned to pop songwriting and recording with a single entitled "All My Life"—written for his third wife Katie Lee Joel. Joel returned to touring in 2006 after a three-year hiatus from the road and has toured extensively ever since, covering many major world cities. In March 2009, Joel resumed his popular Face to Face tour with fellow pianist Elton John. Concerts are scheduled to be held sporadically over two years and travel around the world. The two artists first paired up in 1994, but had not toured together since May 2003.

William Martin Joel was born in the Bronx and raised in the Levittown section of Hicksville, New York. His father, Howard (born Helmut), was born in Germany as the son of German-Jewish merchant and manufacturer Karl Amson Joel who after the advent of the Nazi regime emigrated to Switzerland and later to the United States. Billy Joel's mother, Rosalind Nyman, was born in England to a Jewish family (Philip and Rebecca Nyman). His parents divorced in 1960, and his father moved to Vienna, Austria. Billy has a sister, Judith Joel, and a half-brother, Alexander Joel, who is an acclaimed classical conductor in Europe, currently chief musical director of the Staatstheater Braunschweig.