By Hilary Hughes (In 2018, the Billboard staff released a list project of its choices for the Greatest Pop Star of every year, going back to 1981. Read our entry below on why Lady Gaga was our ...

After a four-month-long exercise, Billboard announced its greatest pop star of the 21st century, but not without controversy.

Lady Gaga and Bruno Mars’ “Die With a Smile” bounds four spots to No. 1 on Billboard’s Pop Airplay chart (dated Nov. 23). The ballad, on Streamline/Atlantic ...