List of Billboard Hot 100 number ones of 2015

The Billboard Hot 100 is a chart that ranks the best-performing singles of the United States.

Its data, compiled by Nielsen SoundScan and published by Billboard magazine, is based collectively on each single's weekly physical and digital sales, as well as airplay and streaming.

During 2015, eight singles reached number one on the Hot 100; a ninth single, "Blank Space" by Taylor Swift, began its run at number one in November 2014.

In total, ten acts topped the chart as either lead or featured artists, with six—Mark Ronson, Charlie Puth, Kendrick Lamar, Omi, The Weeknd and Justin Bieber—achieving their first Hot 100 number-one single.

Mark Ronson and Bruno Mars' "Uptown Funk" was the longest-running number-one of the year, leading the chart for fourteen weeks; it subsequently topped the Billboard Year-End Hot 100.

" Uptown Funk " by Mark Ronson ( pictured ) featuring Bruno Mars spent fourteen weeks at number one, becoming the second longest-running number-one single since the chart's inception in 1940. It later ranked as the best-performing single of the year.
Taylor Swift ( pictured ) earned her third and fourth number-one singles with " Blank Space " and " Bad Blood ".
The Weeknd ( pictured ) earned his first and second number-one singles with " Can't Feel My Face " and " The Hills ".
Wiz Khalifa ( pictured ) earned his second number-one single with " See You Again ". It spent 12 weeks at number-one, tying with " Lose Yourself " and " Boom Boom Pow " as the longest-leading rap single.
" What Do You Mean? " by Justin Bieber ( pictured ) debuted at number one, becoming the twenty-third song to do so.
Adele ( pictured )'s " Hello " debuted at number one, becoming the twenty-fourth song to do so, and the fourth Adele song to top the Billboard Hot 100.