Turnbuckle is an antagonist in Treasure Planet and one of the pirates in John Silver's crew. He is a gray octopus-resembling alien bearing two long tentacles for each of his arms and legs. He served as the helmsman to Captain Amelia, though he may have maintained his position as such during the mutiny. He is one of the last two pirates (the other being Blinko) to die in the film; during the collapse of Treasure Planet, as he and Blinko struggled to escape with their ill-gotten gains, they were caught in the waterfall of gold coins and fell into the lava-filled crevices to their deaths.
In Treasure Planet: Battle at Procyon a continuity error is made as in the game he is alive and tells Jim "beware" while handing him a piece of dark matter, but in the movie he falls to his death at the planet's exploding core.