Music sharing website MusicMagpie recently revealed that 85% of artists with a number one hit over the last 50 years have had their most popular song written by someone else - and their ghost writers are just as famous.
The website analysed chart data from 1966 to 2016 to see which artists wrote their number one hits without help from other musicians.
The results showed some surprising collaborations - singers and artists from Ne-Yo to Katy Perry have all had a hand in writing for big stars.
From Harry Styles to David Bowie, here are 17 artists who have written songs for their chart-topping peers, ranked by their estimated net worth.