Guess the Glamour Shot!

Can you guess the celebrity in this photo flashback?
It's none other than Katy Perry, who posted the pic via her Twitter, saying, "grandma brought this one outta the closet today! #glamourshots" 
Teenage Dream, Katy's new album, is out today. With the title track already at No.5 on the charts, ET reveals the top 5 things you don't know about the music maker: 

Drew Barrymore Ehrinn Cummings Elena Lyons Elisabeth Rˆhm