Unbreakable: The Greatest Hits Volume 1 is the fourth studio album and first greatest hits album by Irish boy band Westlife. The album was released on 11 November 2002. The album consists of all of the group's past singles, along with six brand new songs. Hit single "Flying Without Wings" was re-recorded as a duet with Korean superstar BoA and Mexican singer Cristian Castro, and each respective duet was included on the Asian and Spanish versions of the album respectively. The first single released from the album was "Unbreakable", a UK number-one single. The second single, the double A-side "Tonight / Miss You Nights" peaked at number three in the UK.

Unbreakable peaked at number one in the UK and at number 66 in Australia and sold close to 1.4 million copies in the UK alone. It is also the band's longest charting album. The album was the ninth best-selling album of 2002 in the UK. It managed to re-enter the year-end albums chart of 2007 at number 107. On October 2008, IFPI announced that the album was certified 2x Platinum, exceeding two million sales in Europe. On the year-end album charts of 2008, the album re-entered at number 79 with 191,000 copies sold within the year. The album spent 55 weeks on the UK Top 100 Albums chart.

In 2008, the album was re-issued in an exclusive two disc edition, entitled "Unbreakable: The Greatest Hits - 2008 NZ Tour Edition". The package featured the album, with the same tracklisting, plus the "Live At Wembley" 2006 concert DVD. It peaked at #1 on the albums chart there, and achieved 2x Platinum status, with more than 30,000 copies sold. The album finished at #19 on the 2008 New Zealand Year-end charts.