O

O is a cerulean blue Letter. He has one eye on the top of his body, making him a cyclops. His hole acts as his mouth. He moves around by rolling. In his superhero form, he has additional muscles, his eye is moved to under his body, along with the addition of a new mouth. As a lowercase Letter, o ganged up with l to confront n by wanting to bully him. After l scared away r, i, e, d and s, l slingshot o into n and then mocked him. Then, o and l laughed about bullying and hurting n upon making fun of him. Irritated from this, f took revenge on l and o for attacking n by spelling the word fart to embarrass l in front of b, c d, e, and h laughing at him. Then f and n laughed about pranking l and o. After that, l got mad and retaliated with o to bully f. They confronted him for pranking them in front of the letters by beating him up upon making him cry out gems in response when he reacted in pain. When f walked to r, i, c and k to spell the word 'frick', o said his catchphrase, drawing the attention of all the letters to betray f. Then o, l, and m turned on n and forced him to join their good side and they watched f run away into his cave after all the letters rejected him. Sometime before F's attack, O grew into an adult.

In O, O introduces himself, in front of an exhausted F. He then does a Sailor Moon-esque. transformation. After his transformation he smacks F.

In Q, O along with M seems mad about N losing his gem.

In R, O flies away with L after pushing N for losing his gem.

In S, O along with L freeze F after slurping down S. Unfortunately, F uses N's gem to conjoin them and steal their gems.

In Y, O along with L witness the ray shot by N through F.

In Now I Know My ABCs, o along with l try to block n, but l and o, along with m, are surprised that n chose to side with f. Angered, l pushed f, and o pushed n. In 3, he, alongside the other Vowel Letters, was dancing until the Calculator Ship flies by them. The Letters noticed B and X being kidnapped inside a button, and they were ready to chase the ship until L gets into O's hole. They turn into their super forms and fly to the ship. After they made their way to the ship, they were near X until 2 is ready to shoot his teeth at them, and he did. The Letters got ran over by BIKE, but rejoin the chase. He also witnessed 1's clone and 2 making 3. Later on, he witnessed a fight between J, K, and 3. After L used his period gem to freeze 3 and shake the Calculator's continents out, O conjoins the Numbers with his colon gem.

In 4, after the VAN and L go to F's cave, O watches from a distance, but noticed that 1 was braking his colon gem to set the Numbers free. He, alongside the other Letters, got ran over by the Math-Machine. Later on, when the BIKE and g crash into 4's tail, O rescued BIKE and g and used himself as a wheel. They were chasing the Numbers, and when F won the tassel between him and N, O used his gem to repair the link between the gems, giving an open door for the Numbers to catch up. However, O's gem's powers faded out and he and N gaze upon the ship spelling "NO", sad about their best friends. O used to be a very boastful and mean letter as he bullied f and n when younger and in the old timeline, looked down on N after the latter lost his semicolon gem. In the new timeline, O is more mellow and friendly as seen when he danced with the vowels, acted as a spare tire for the BIKE and helped N try and stop the calculator ship.