Octi is a purple stuffed octopus wearing a small black hat. Octi is Bubbles' most prized stuffed animal. As seen in The Powerpuff Girls Movie, it was given to Bubbles by Professor Utonium, Bubbles' creator.
- In the original series, Octi had two episodes focused on him: "Octi Evil" and "Octi-Gone". In the reboot, he had one episode focusing on him: "Little Octi Lost".
- Despite being an octopus, Octi only has four legs in the first four seasons. However, this may have been due to eight legs being hard to animate.
- Octi wears a hat similar to the Mayor's hat.
- Octi is similar to Oswald the octopus from the Nick Jr. series.
- In seasons 5 and 6, he has six legs instead of four.
- In the 2016 reboot, Octi has no hat. However, his hat can be seen in the opening sequence.