This is a list of artists who have reached number one on the UK Singles Chart as recorded by the Official Charts Company. Artists are listed alphabetically and separately if more than one artist is credited on a song (e.g. John Travolta and Olivia Newton-John each gets separate credits for their duet from Grease). Artists who performed on a song but not credited are not included, although notable cases may be recorded in the Notes column. In the 20th century guest musicians or singers were sometimes credited and sometimes not, while it became more common to include featured artists in the early 21st century.