Kai Green is a human from Earth in Ben 10.
In Ben 10: Protector of the Omniverse, she has her original series appearance, but she is as tall as Ben and her shirt is longer.
In Ben 10: The Omniwars, she has her Omniverse appearance, but with her hair let out, and she now wears full khaki pants and black gloves. In her Loboan form, she has pink eyes, a red and black shirt, and khaki shorts. She does not have a long mane.
In Ben 10: Unbound , she has her Omniverse appearance but her hair is let down and has different earings. Her khaki pants are longer but are short.
In Bellwood: The Animated Series She has her Omniverse appearance, but she wears a long-sleeved shirt and a tight khaki skirt.
In Ben 10 Evolution Generation She has her Omniverse appearance but she doesn't have the plates on her thighs.
In Ben 10: Cosmic Force, she has her Omniverse appearance but she wears a white and red cheerleading uniform and sneakers.
Ben 10: Protector of the Omniverse
- Not Feeling Like Myself (first reappearance)
Ben 10: The Omniwars
- Always Cry Wolf (first re-appearance)
Ben and Kai went on separate terms after Ben revealed that he was going away to Madison Tech, several states away from Bellwood. However, Kai is still good friends with Ben and contacts him daily. Later on, Ben and Kai will have a conflict concerning Ben's new relationship with his classmate, Samantha Everhart, which she never knew about.
- Wolf Bane
- Wes Out
- War of the Worlds Part 1 (John Smith 10)
- War of the Worlds Part 2 (John Smith 10)
- Above and Beyond (John Smith 10)
- The Ultimate Enemy Part 1 (John Smith 10)
- The Ultimate Enemy Part 2 (John Smith 10)
- The Ultimate Enemy Part 3 (John Smith 10)
Kai is Terry's first and currently only love instrest.
- Terry 12: The Ghost King
- If Rocks Could Kill