Katy Perry and The Kardashians team up

The crossover we never knew we needed.

Katy Perry and The Kardashians!!! 

Turns out Kim Kardashian is a HUGE Katy Perry fan. 

Kim was at Katy's recent show 'PLAY' where she went backstage to sing the pop star's praises.

Kim wasn't the only fan there, as was North, Kim and Kanye's daughter. 

Katy invited North up on stage.

Watch the video here: