The captain who leads the Octonauts. He is a polar bear. He has a strong sense of responsibility and a warm, caring personality. He is a magnanimous leader who always puts his crew first. He always carries his Octo-compass, which is equipped with various functions. When the Octopod isn't functioning properly, he takes the helm and pilots it himself. True to being a polar bear, he possesses immense strength.

The Octonauts' lieutenant. He is a cat. He has an active and proactive personality, always moving at his own pace. He wears a black eyepatch covering one eye. Coming from a family of pirates, he naturally enjoys and loves exploration. When Captain Barnacles is unable to lead the Octonauts, he takes charge and leads his comrades himself.

The Octonauts' medic. He is a penguin. He has a somewhat timid and shy personality. However, he is a brave crew member who knows how to step up when needed. He always carries his medical kit in his hand. He is highly skilled at both applying and removing bandages. He is also Kwazii's best friend.

The Octonauts' communications and technical officer. She is a dachshund. She has a cheerful and bright personality. In the Octopod control room, she handles tasks such as tracking targets and surveying terrain. She loves taking photos and even works as a photographer. She seems to have the most mechanical knowledge in the Octonauts after Tweak.

The Octonauts' marine biologist. He is a sea otter. He is extremely knowledgeable about marine life. However, he can be a bit clumsy at times. He has a strong model-student streak. Machines are definitely not his forte, and he can be physically awkward. He is the one who originally brought the Vegimals. He is the only one who can understand what the Vegimals are saying.

The Octonauts' engineer. She is a rabbit. She generally has a cool and extroverted personality. She wears a pink headband and has tools attached to her belt. All the machinery and GUPs in the Octonauts are Tweak's creations. Being a rabbit, she is very fond of carrots.

The Octonauts' oceanographer and founder. He is a Dumbo octopus. He has a somewhat cynical personality. He always wears a monocle. He rarely goes out into the field, but he assists the crew from within the Octopod. He is the oldest member of the Octonauts and possesses even more knowledge of marine life than Shellington.

The Octonauts' cook and gardener. He is a Vegimal (half-tuna, half-turnip). He is the leader of the Vegimals that Shellington brought back. He has a playful and cheerful personality. He is also Shellington's close friend.