Mainstream music acts will tour with other acts and guest star on a track here and there, but for some reason they almost never combine their musical super powers to form supergroups, which is a shame.
Sometimes their contracts prevent them from teaming up, but more often than not the artists themselves (and their egos) shut down the supergroup idea before it can take shape.
In 1969 Jimi Hendrix and Miles Davis were looking to form a group and record an album together, so they sent a telegram to Paul McCartney inviting him to play bass on the album.
But that amazing supergroup never got to form because, according to the response letter from his personal assistant, Paul was on vacation in Scotland and wouldn't be available for a few weeks.
It's unclear if Paul knew about the offer, but when he was asked in the same year whether The Rolling Stones, Bob Dylan and The Beatles should record an album together he and Mick flat out said "NO!"
The idea was proposed by producer Glyn Johns, who wanted to use the album as his own kooky version of Battle of the Bands:
Johns had the whole thing planned out, too. He would take all the best material from each group, have them compete for best rhythm section, and then have the winners perform that song on the album -- which makes us wonder why The Hunger Games couldn't just have been that?
According to Johns, quite a few members were down with the elaborate project/musical death match, but in the end bigger egos prevailed:
"Keith and George thought it was fantastic. But they would, since they were both huge Dylan fans. Ringo, Charlie, and Bill were amicable to the idea as long as everyone else was interested. John didn't say a flat no, but he wasn't that interested. Paul and Mick both said absolutely not."