Crossbow: A bow set horizontally on a stock, making it possible to carry it loaded and aim it more like a gun. its missle is called a quarrel or a bolt. They are extremely powerful; typically a crank or other tool was used to cock them. Medieval crossbows had greater range than bows, but were much, much slower to use (about one quarrel per minute, versus 6 - 12 arrows per minute for a bow). Modern crossbows are somewhat quicker to use, but still not nearly as quick as a bow.
Use these statistics for all average-size crossbows, from medeival times to modern. For smaller crossbows (such as the pistol-sized modern version), reduce the range, Initiative, and Damage proportionately.