Octavius Octopus is a background student at Charles Darwin Middle School. He is an octopus who moves around the school, by sitting in a bucket of water on wheels and pushing himself around with his side tentacles. He had his first speaking role in "Bubble or Nothing".
In "Guano in 60 Seconds", he, and two other cephalapod students, Daniel and Noah, were in Miss Loon's Class, learning how paint with their own natural ink. The class was moved to a moving vehicle at the time, which hit a speed bump and caused them to mess up their paintings, which ended up making them better. Octavius' painting was a replica of Starry Night.
In "I Got a New Aptitude", Octavius took the career aptitude test. He used eight pencils, one in each tentacle, getting him through the test eight times as fast. His first name was revealed when he wrote it down.