Who was the king of pop in 1950s?

There was no universally recognized "King of Pop" in the 1950s. The term "King of Pop" is commonly associated with Michael Jackson, who rose to prominence in the music industry in the 1980s and maintained significant popularity throughout his career until his death in 2009. The 1950s featured several prominent and influential popular music artists, but the title "King of Pop" was not widely used during that era.