Laboon

Laboon is a whale of staggering size, rivaling the Sea Kings of the Calm Belt, with a single eye many times larger than the Going Merry itself. His hide is black, rendered blue in the anime, and he sports short fins and a fluked tail. Years of ramming Reverse Mountain have left his head a web of scars, over which a rough copy of the Straw Hat Jolly Roger was painted after he met the crew.

His interior holds a maze of metal chambers and passages, fitted to manage his habit of swallowing vessels that provoke him. The largest chamber, built into his stomach, even houses an artificial island and a cabin for Crocus, coated in a material that mimics a daytime sky and gives off its own light. As a baby fifty-two years earlier he was only the size of a small dinghy, with rounder teeth.

Deeply emotional and remarkably perceptive for a whale, Laboon shows the patience and devotion of a true friend, forming powerful bonds with the Rumbar Pirates, his caretaker Crocus, and later the Straw Hats. He is also stubborn, refusing to accept that his old companions had died despite Crocus explaining it again and again, and he carries a playful streak.

In his early years he was a cheerful calf who attached himself to the Rumbar Pirates, but their departure shattered his happiness and sank him into depression. A blind hope of reuniting with them drove him to batter the Red Line for decades, trying to break through to the West Blue. When Luffy battled him and painted the crew's mark on his head with a promise to return, Laboon honored that vow and stopped slamming the mountain so the symbol would not wash away.

More than fifty years ago, a lost and lonely Laboon began trailing the Rumbar Pirates, who cheered him with song and took him in, with Brook giving him his name. When the crew set out for the Grand Line they tried to leave the baby behind for his safety, but he followed them over Reverse Mountain, where they met the lighthouse keeper Crocus. After repairs, they bid him farewell and entrusted him to Crocus, promising to circle back within a few years.

Crocus eventually sailed with the Roger Pirates to learn the crew's fate, returning to tell Laboon they had fled the Grand Line. Unwilling to accept it, the whale turned and rammed the mountain for the first time, gathering scars over the years that followed. When the Straw Hats arrived, Luffy picked a fight with him and renewed his hope, leaving the painted insignia as a pledge of a future rematch.

Laboon stayed at Twin Cape thereafter, roaring with joy when Brook joined the crew, and remaining with Crocus through the years, the Jolly Roger still intact on his face. In the Final Saga he wailed as earthquakes shook the world, then listened with Crocus to Vegapunk's worldwide broadcast.