| Please note the following:
Katy Nutkiss Calvin, or simply Katy, is the sister of Cody. She first appeared in Cody's Sister!. Katy is dating a Barbie doll similar to how Cody is dating a Ken Doll. Whenever someone asks Katy a question she responds with an interesting fact. She also breathes very deeply just like Cody. In the video Cody's Sister, Bowser Junior and Joseph liked his sister, but then they found out she was just like Cody. She is not really a popular character. She was the main character of Cody's Sister, but we do not know if she will ever be in another video.
- During the scene where they are watching "Butter Knife", Cody reveals that she is allergic to popcorn.
- She appears to have the same fetish as Cody with dating a doll.
- When they first call Cody, he reveals that his sister now lives in Wisconsin.
- Katy was born 5 minutes after Cody, which basically makes her his little sister.
- In Mario Plush Collection!, Logan revealed that the Katy plush was a Cody plush that had pink fabric sewed on.