Best Coast

'ALL those who defend our right to live freely should be able to serve freely! There are THOUSANDS currently serving!' Perry wrote.

Fellow musicians are flooding social media with messages of support for Kesha.

The Best Coast frontwoman writes, "Did anyone call The Beatles ‘whiny babies’ or ‘needy’ for singing the lyrics ‘This boy wants you back again’?"

Grab your pencils and peep our list of the 10 Most Anticipated Pop Acts performing at SXSW 2015!