In Spelunky HD, an Arrow can be found when activating or breaking an Arrow Trap. The resultant projectile can then be thrown to deal 2 damage. Contrary to the former non-HD version, when an arrow hits its target, it becomes a headless arrow instead of disappearing.
Headless arrows deal no damage but can be used to break pots, chests and Mystery Boxes open from a distance. It may cause Powder Boxes to explode. It can knock-out a Spelunker or a Damsel. It can also cause a Spinner Spider to fall from its web and jump around. It has no effect on flying bats but can make a Snake, a Cobra or a Giant Spider stumble for a second. Thus, headless arrows appear to be one, if not the only, throwable object in the game that can be used almost safely in every condition.