A cabin boy is a crew member on a ship, almost always the youngest person aboard, who waits and performs various errands on a ship, such as relaying messages, carrying buckets of food across the ship, scrubbing the deck, and keeping the wheel steady during good weather. They're typically at the very bottom of the ranks on a ship.

In stories, the cabin boy tends to be either a preteen or a young teenager, though they can sometimes be in their late teens or a young man. Either way, they're far younger than the rest of the crew. In a story set at sea, if the cabin boy's not the protagonist, they'll usually be a