The color green is associated with plants, and by extension, nature and the earth. Characters with a strong connection to nature and the earth tend to have green eyes to highlight this.
- Flora from Winx Club has green eyes. Which fits seeing how she's the fairy of nature.
- Most Earthbenders in Avatar: The Last Airbender have green eyes, including Toph although her's are a mix of green and grey due to her blindness.