Goo is the secondary tritagonist of the series. She is a blue, mermaid-like girl with yellow hair, a silver bow, and the power to fly and spit balls of clay. She is a friend of Gumby and is voiced by Marina Elbertson. It is unknown if she would later be voiced by Grey DeLisle-Griffin in the upcoming reboot.
Goo has a sweet and kind nature, though she also has the tendency to be tricky & clever.
At first she crawls on her stomach, but in later years, she walks on her fins. Goo has the power to fly. She can also slide on her stomach, almost gliding, and can throw balls of blue goo from her body.