"All I Ask of You" is a song from the 1986 English musical The Phantom of the Opera, between characters Christine Daaé and Raoul, originally played on stage by Sarah Brightman and Steve Barton, respectively. It was written by Andrew Lloyd Webber, Charles Hart and Richard Stilgoe, and solely produced by Lloyd Webber. An operatic pop piece, its lyrics serve as dialogue between the two characters and discuss themes such as commitment and romance. Like Lloyd Webber's song "The Music of the Night", "All I Ask of You" was compared to the music found in Giacomo Puccini's 1910 opera La fanciulla del West.

Critically, the song has generally been regarded as one of the finest cuts made for The Phantom of the Opera. It was released as a single by Polydor Records on 26 September 1986 on 7-inch and 12-inch, performed by Brightman and Cliff Richard. The song achieved commercial success in several territories, including in Ireland and South Africa, where it topped the charts and the United Kingdom, where it peaked at number three. It was later certified Silver in the latter country for shipments of 250,000 copies. "All I Ask of You" has been covered by multiple artists, including The Shadows, Lloyd Webber's brother Julian, Elaine Paige, and Jackie Evancho. Susan Boyle and Donny Osmond, Josh Groban and Kelly Clarkson, and Marina Prior and Mark Vincent have also continued with duet versions of the song.

A notable cover of "All I Ask of You" was recorded by Barbra Streisand for her studio album Till I Loved You (1988). It was released as the record's second single on 15 December 1988 by Columbia Records as a 7-inch, 12-inch, and CD. It was generally noted as a standout track on Till I Loved You and was commercially successful, entering the charts in the Netherlands, the United Kingdom, and on the United States' Adult Contemporary chart.