What is the best selling Metallica single in history?

The best-selling Metallica single is "Nothing Else Matters," released in 1992 as part of their self-titled album, also known as "The Black Album." The song's universal appeal and relatable themes of love and yearning contributed to its massive success. "Nothing Else Matters" has sold over 10 million copies worldwide, making it one of the most commercially successful rock singles in history.