He is not a true villain, just a hungry whale. It isn't a crime for an animal to eat.
Monstro is first mentioned in the film when Pinocchio and Jiminy Cricket receive a message from the Blue Fairy that the whale has swallowed Gepetto, Figaro, and Cleo when the toymaker took to sea in search of his son. The three are still alive, inside Monstro's belly. Against Jiminy's warnings, Pinocchio resolves to find and rescue Gepetto. Though Jiminy tries to dissuade Pinocchio, warning that Monstro is "a whale of a whale... he swallows ships whole.", he does not hesitate to join the wooden boy in his search at the bottom of the sea. The two search for Monstro; mention of the whale's name causes the sea creatures to flee in terror. Meanwhile, in Monstro's belly, Gepetto and Figaro are trying to catch fish to eat. The toymaker tells Figaro that he fears that they will starve in the belly of the sleeping whale.
Monstro wakes at the sight of a school of tuna swimming nearby. Opening his great eyes, the whale pursues the fish, mouth open, tearing through the ocean. When Pinocchio sees Monstro approaching, he flees for his life, pushing past the tuna, though he is nevertheless consumed by the beast. The sprightly Jiminy escapes the creature's jaws, but, on discovery that Pinocchio has been swallowed, tries to enter Monstro's now closed mouth. Inside the whale's belly, Pinocchio, reunited with his father, proposes that they escape in a raft (constructed by Gepetto) when Monstro opens his mouth. When told that "everything comes in... nothing goes out" of Monstro's jaws, the wooden boy suggests that they start a fire to make the whale sneeze them out, while Gepetto says that it will make him mad.
Monstro once again opens his eyes, this time to find smoke rising from his blowhole. He begins taking deep breaths; while his mouth is open, Pinocchio, Gepetto and the pets try to escape; they succeed when Monstro finally sneezes, sending them flying out to the sea. After another powerful sneeze, Monstro douses the fire inside him by taking in water. Just as Gepetto predicted, Monstro becomes very angry and the enraged whale pursues the raft while Pinocchio and Gepetto row for their lives. Monstro dives underwater and emerges underneath the raft; Pinoccho and his father row away in time, but when Monstro leaps after them, they are forced to jump into the sea. The whale smashes the raft into pieces with his tail. Pinocchio saves his father from drowning and pulls him to shore, with Monstro in hot pursuit. As the whale builds up speed, the waves drifting from the cliffs of the shore hinder Pinocchio. Monstro leaps into the air, aiming to consume and kill the two. Finally, paddling madly, the wooden boy swims through the hole in the cliffs just as Monstro crashes into the rock, presumably killing himself. The force of the impact sends Pinocchio and Gepetto flying onto the beach. As the toymaker comes to, Jiminy, Figaro, and Cleo are washed onto the shore. Pinocchio, however, has been killed by the blow. The puppet is later brought back to life, and turned into a real boy, by the Blue Fairy.
Behind the ScenesEdit
Joe Grant's Character Model Department was responsible for the design of Monstro the whale. Models were constructed both of Monstro himself and of his belly, complete with skeleton. In addition, inspirational sketch artist Gustaf Tenggren created a watercolour of Gepetto in Monstro's belly.
Apparently, Monstro is a combination of a Sperm Whale and a Baleen whale, since it has a square head and teeth like a Sperm Whale, and a folded underbelly like a Baleen Whale. His appearance does not fit any real life species of whale.
The animation of Monstro was originally to be assigned to Vladimir Tytla (animator of Doc, Grumpy, T-Rex, and, later, Yensid, Chernabog, Dumbo, and Friend Owl), but, perhaps out of worry that Tytla might get carried away, Disney eventually assigned Wolfgang Reitherman to the task. He animated Monstro as a cunning creature with a brain, making his pursuit of his prey all the more frightening. To Reitherman can also be attributed, to an extent, the timing and staging of Monstro's chase sequences, which were timed to suggest the whale's great weight and power. Reitherman drew a set of sketches for a discarded sequence showing Monstro consuming Gepetto's boat; Monstro was to emerge suddenly on the otherwise serene sea scene, first looking like a large mound before revealing his teeth and swallowing the boat in one movement before disappearing underwater once more.
In Kingdom Hearts, Sora, Donald, and Goofy are flying away from Agrabah to get to their next destination; they spot something huge flying towards them on the Gummi Route. They quickly realize it is a massive whale, but cannot get out of the way before the beast swallows their ship whole.
Inside Monstro's flooded mouth, the trio finds Pinocchio again and meets his father Geppetto in a broken ship. While speaking with Geppetto, Pinocchio slips off to explore Monstro. Sora and his party quickly run after the puppet into the bowels of Monstro. There, he finds Riku; the two friends exchange some quick words before Riku runs off with Pinocchio, hinting at Riku's newfound darker nature.
Sora, Donald, and Goofy chase the two through the whale, until he eventually finds them in a large circular chamber that are the bowels of the beast. Pinocchio is taken captive inside the Parasite Cage Heartless. Sora and Riku team up to take down the Heartless, but are unable to completely destroy it. Riku takes Pinocchio; his words hint to Sora that there is something different about his old friend. Sora tracks the puppet to the Stomach, where Riku and the Heartless attempt to take Pinocchio's heart, but fail. Riku flees as Sora enters the belly of the beast where he defeats the Parasite Cage once and for all and rescues Pinocchio.
From all the commotion in his organs, Montro spits out the Gummi ship and the trio to prevent any more trouble. Pinocchio and Geppetto also escape and set up a shop in Traverse Town.
In Kingdom Hearts: Birth by Sleep: Final Mix, Monstro appears as a Mirage Arena boss in the Monster of the Deep event.
In the original Italian story of Pinocchio, instead of a whale it was a giant shark ("il pesce cane"), which the author had drawn from folklore concerning a terrible phantom shark which mothers warned their children would swim up and swallow them if they swam too far out to sea without supervision. Why Disney chose a whale instead of a giant shark is still uncertain.