Top-selling musical artists of the 1960s: 2 and 1
No. 2 - Elvis Presley (131,658,000)
How much does it say about the greatness of the Rolling Stones that the iconic Elvis Presley doesn't far outsell them in Presley's most commercially successful decade? But I don't want to detract from Elvis because selling 131 million records in a single decade is more than most artists could ever do. And Elvis didn't produce a ton of studio albums in the 1960s either. He produced six total, but only two after 1962. And one of the two he released between 1967 and 1970 was a religious record.
1967's How Great Thou Art was actually Elvis's top-selling record of the decade and sold more than 3 million copies. Before that, his best had been 1957's Elvis' Christmas Album which also sold 3 million copies. There could be a strong argument that musical artists like Dylan and Simon and Garfunkel were much more original and creative than Elvis as they wrote their own songs, but no solo artist was more of an icon in the 1960s than Elvis Presley.
No. 1 - The Beatles (376,924,000)
Just look at that number of record sales. The Beatles not only trounced the other performers listed here - they sold as much as Simon and Garfunkel, the Rolling Stones, and Elvis combined - but the number of records sold by the Beatles in the 1960s alone was nearly 200 million more than any other artist in any other decade. Plus, the Beatles simply changed music in a way no other musical artist ever has.
Massive world tours? Yep, they started that. Change the way records are made? Yep, they did that too.
The Beatles stopped making LPs in 1970 so almost all their output is in one decade as a band. (Paul McCartney and John Lennon, especially, would do very well as solo artists too.) Three albums, Sgt. Pepper's Lonely Hearts Club Band, the White Album, and Abbey Road all sold at least 11 million copies in the US alone. The Beatles were special and we will likely never see another band who can change the world the way they did.