A Boarding Hook (or "grappling hook") is a composite hook attached to a rope, designed to be thrown or projected a distance, where its hooks will engage with the target. Grappling hooks were originally used in naval warfare to catch the rigging of an enemy ship so that it could be drawn in and boarded.

The most common design consists of a central shaft with a hole at the base of the shaft, called an "eye" to attach the rope, and three equally spaced hooks at the end of the shaft, so arranged that at least one is likely to catch on some protuberance of the target.