Katy Perry in Final Fantasy Brave Exvius
Katy Perry created a new song for Final Fantasy Brave Exvius called "Immortal Flame." Not only that, but those who participate in an in-game event on December 12 will get to obtain "Popstar Katy" as a playable character.
This character, featuring Perry’s pixel design in a red costume, is an iconic look from her performances during her “Witness” concert tour. Additionally, other character designs featuring Perry in her other attire will be available in future in-game events.

As always, Final Fantasy Brave Exvius is a free-to-play game supported by optional in-app purchases. You can get it now via the Apple App Store, Google Play, and the Amazon App Store.

I apologize for not having a larger image of Katy's sprites. This is all that was provided and I tried to enlarge it without destroying the look too much.