Getty Images, 2

Quick, what do Radiohead, Adele, One Direction and Ozzy Osbourne have in common? As of today, "nothing" is no longer the correct answer. Each of these disparate artists—along with more than 100 other musicians—have added their names to the growing list of people calling on Russia to free Pussy Riot.

Although the feminist punk collective recently unleashed a Putin-bashing video calling Russia a "Red Prison," two of the members who participated in the group's 2012 "punk prayer" still remain behind bars for offending the Russian Orthodox Church.

Although international celebrities such as Paul McCartney, Madonna, Bjork, Bruce Springsteen and U2 have repeatedly called for their release, this new open letter from Amnesty International adds a variety of new voices to the chorus calling for their release.

In addition to Harry, Zayn, Liam, Niall and Louis (each member of 1D separately signed the petition), Adele, Ozzy and Radiohead (who signed as a unit), Ke$ha, Arcade Fire and fun. also added their names to the list. Oddly enough, Aerosmith's Joe Perry is listed here, but not Steven Tyler. Perhaps he's a closet member of the Russian Orthodox Church.