Cuttlefish

"This unreasonably attractive gentleman goes by the name of Cap'n Cuttlefish. He’s a decorated hero who fought in the Great Turf Wars of legend between the Inklings and Octarians. He now keeps solemn vigil over Octo Valley, watching for any fishy behavior. Though his clothes may be tattered, his heart is pure and nothing escapes his razor-sharp gaze. He also TOTALLY didn’t write this post."

- Live from the Squid Research Lab

Cap'n Cuttlefish (Japanese: アタリメ司令 Atarime Shirei) is a main character in Splatoon, and the only known adult Inkling. He acts as a guide for the protagonist, issuing them the Hero Suit and title of Agent 3 in Octo Valley. He is also the grandfather of Callie and Marie.

History
Prior to the ultimate end of the Great Turf War, Cap'n Cuttlefish served as leader of a division called the Squidbeak Splatoon alongside Ammoses Shellendorf, Judd, and two unidentified Inkling soldiers. It is unknown what he did between the end of the war and the beginning of Splatoon, but he seems to have changed little.

As of the story of Splatoon 2, Cap'n Cuttlefish is off traveling with Agent 3 for some kind of research trip "at the cape". What this research might be is currently unknown.

Personality and traits
Cap'n Cuttlefish is a decorated hero who fought in the Great Turf Wars of legend between the Inklings and Octarians. He now keeps solemn vigil over Octo Valley, watching for any fishy behavior. Though his clothes may be tattered, his heart is pure and nothing escapes his razor-sharp gaze.

Cap'n Cuttlefish's favorite food is crab cakes❌/biscuits, as pointed out both by himself and Agents 1 and 2. He is often distracted by them, giving DJ Octavio the chance to escape from his snow globe prison.

Trivia

 * In the main hub of Octo Valley, the player can ink Cap'n Cuttlefish; he will eventually shake off the ink. However, it takes a considerable amount of ink to completely cover him, though, suggesting that he may be more resilient than the average Inkling, despite his age and frail appearance.
 * His cane is one of many Bamboozlers used by Inkling soldiers in the Great Turf War. However, he has never been seen to use it for its original purpose in-game, only as a cane. Interestingly, he is shown to be using it in a credits art.
 * On the corner of his shack, Cap'n Cuttlefish has taped up two small photographs of his grandchildren, one of Callie and one of Marie.
 * His shack appears to be filled books and zapfish dolls, along with pictures of octarians in the front.
 * During the initial tour of Inkopolis upon starting the game for the first time, he is referred to as a "creepy old dude".
 * The Legendary Cap is modeled after Cap'n Cuttlefish's signature hat.