Westlife is an Irish boy band, formed in 1998 in Sligo, Ireland. They disbanded in 2012 and reunited in 2018. The group currently consists of Shane Filan, Markus Feehily, Kian Egan, and Nicky Byrne.

They are the top act with most Number 1 debuts on the UK Singles Chart, with all 14 of their chart-toppers landing there in their first week. They have the second most certifications for a boy band in the UK Singles Chart after Take That and the most singles certifications for a pop band in the UK number-one singles artists chart since The Beatles.

The band has sold over 55 million records. They are holders of the following Guinness World Records: first to achieve seven consecutive number-one singles in the UK, most public appearances in 36 hours by a pop group, most singles to debut at number one on the UK chart, and top-selling album group in the United Kingdom in the 21st century.

Westlife is one of the most successful musical groups of all time, among the highest-profile acts in 2000s popular culture in most territories worldwide, and one of the few boy bands to have continued success after their commercial peak. On the best-selling boy bands of all time list, they are currently eighth worldwide along with the biggest-selling boy band from Ireland in history globally.