Demi Lovato turns 21 today (Aug. 20), and since we've already looked at her best hairstyles, we've decided to celebrate her big 2-1 by taking this walk down memory lane and reliving her many, many magazine covers over the years.

From her days as a fresh-faced Disney teen -- wait till you revist her shared cover with Selena Gomez, who just turned 21 in July -- to her more smoldering, sultry post-rehab covers, there are two things you can always expect from a Demi Lovato mag spread without fail. One is that she won't have the same hair cut or color as her last cover. Second is that she will look absolutely gorgeous!

Happy birthday Demi! You can consider your pals at PopCrush to be Lovatics.

Check out this rundown of some of her best magazine covers, in no particular order.

Cosmopolitan
Cosmo on Campus
Cosmopolitan
Demi
Dolly
Fashion
GL
Creme
Latina
Self
Seventeen
Seventeen
Teen
Teen Vogue
Teen Vogue
TV Guide
You