The captain who leads the Octonauts. He is a polar bear. He has a strong sense of responsibility and a warm, caring personality. A true leader who always puts his teammates first. He always carries his Octo-compass, which is equipped with various functions. When the Octopod is not functioning properly, he takes the helm and pilots it himself. Being a polar bear, he is incredibly strong.

The Octonauts' lieutenant. He is a cat. He has an active and independent personality. He wears a black eyepatch covering one eye. Coming from a family of pirates, he enjoys and loves exploration. When Captain Barnacles is unable to lead the Octonauts, he takes charge of the crew 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 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 scanning terrain. She loves taking photos and also 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 studious streak. The thing he is worst at is definitely machinery; he tends to be physically uncoordinated. He is the one who brought the Vegimals to the crew. 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 on her belt. All the machinery and Gup vessels of the Octonauts are Tweak's creations. Being a rabbit, she really loves carrots.

The Octonauts' oceanographer and founder. He is a Dumbo octopus. He has a fairly 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 in. He has a playful and cheerful personality. He is also Shellington's close friend.