Both ladies love to show their wild sides through their wardrobe choices and the VMAs have always been a great place for them to show off their latest eye-catching ensembles.
While Gaga might have worn the most shocking ensemble when she debuted the meat dress, Katy definitely wins the "Fun Fashion" award.
She's worn a square yellow cube on her head, brightly-colored wigs and...well, watch the video above and see for yourself.
Then, tell us which one of Katy's outfits is your favorite.
Don't forget to watch the VMAs this Sunday, where Katy, Miley Cyrus, Drake, Lady Gaga and many more will be performing.
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Gallery | MTV VMA: Moments We'll Never Forget!