Justin Bieber is ranked No. 8 on the chart. Billboard rated him from the "teen pop phenomenon" in the early 2010s with the mega-hit Baby , then gradually reached the peak of his career. At the age of 30, Bieber has 23 Grammy nominations (winning 2), 8 No. 1 albums on the Billboard 200, 8 songs topping the Billboard Hot 100 chart, 33 Guinness World Records, 26 Billboard Music Awards, 4 RIAA-certified diamond discs and an estimated 150 million albums sold throughout his career. Photo: GQ .

Billboard said the young singer has been a pop icon for more than a decade. He set a new standard for future pop artists by "being a pioneer in using the media to his advantage, without the support of radio or MTV to achieve success." Photo: Wire.

Right behind Justin Bieber is Ariana Grande . She is a prime example of how a child star who started out as an actress can become an outstanding pop star. Over the past decade, Ariana has created many hits in the midst of a volatile and constantly changing music market. Photo: Vanity Fair .

From The way, Side to side, No tears left to cry, Thank u, next , 7 rings to Rain on me ..., Ariana Grande has gradually become a "digital music queen". Ariana's current position is a testament to her talent and persistent, long-term efforts over the years, Billboard commented. Photo: Shutterstock .

Ranked among the 10 greatest pop superstars of the 21st century is Adele - one of the most commercially successful female singers of the 2010s. Starting her musical career in 2007, just 3 years later, Adele became famous worldwide with the hit Rolling in the Deep, which brought her a Grammy Award. To date, the "British nightingale" has set musical records that few artists have achieved before. Photo: CBS .

Adele has had 5 songs topping the Billboard Hot 100 chart ( Rolling in the Deep , Someone like you, Set fire to the rain, Hello, Easy on me ), 3 albums No.1 on the Billboard 200 (21, 25, 30). In addition, she has 16 Grammy gold trumpets, 3 MTV Video Music Awards and 18 Billboard Music Awards... Photo: People .

Usher is ranked No. 11 on the Billboard charts. After a brilliant peak in the 2000s, Usher has affirmed his position as one of the greatest pop and R&B artists of the century. The 8-time Grammy winner is having a very exciting comeback year. He just celebrated 30 years of music career and 20 years since the release of his classic Confessions. The singer also performed at the Apple Music Super Bowl LVIII Halftime Show in February, which had 123 million views - setting a record for the most watched halftime show in history. His ninth studio album Coming Home debuted at No. 2 on the Billboard 200. This past August, he also kicked off his Past Present Future world tour. Photo: WSB .

Right behind Usher is Eminem . After three years at the beginning of the century with global hits, Eminem reached a peak that no rapper has ever reached since. The Rap God owner “transformed from underground rapper to superstar, reaching commercial heights and levels of popularity as a solo artist that previously only stars from the golden age of pop music in the 1980s could achieve.” Today, he remains a top rapper and is loved by millions of viewers. Photo: REX .

Nicki Minaj is ranked 13th on the list of the greatest pop superstars of the 21st century. Few figures in 21st-century pop culture and music, or hip-hop history in general, can match her influence and immense talent, Billboard said. Dubbed the “Queen of Rap,” Minaj has received many prestigious awards throughout her career, including 6 American Music Awards, 12 BET Awards, 4 MTV Video Music Awards, 4 Billboard Music Awards and 10 Grammy nominations... The owner of the hit Anaconda has also sold about 100 million singles worldwide, making her one of the best-selling music artists in the world. Photo: WTYE.