Lethal is a type of damage used in the health system of White Wolf's games. Like the other damage types, it was introduced in the Revised Storyteller System and then incorporated into the Storyteller System in the Revised Edition World of Darkness games. It is also a feature of the Storytelling System's health system.
Lethal damage represents types of injury which can easily cause serious danger, and is perhaps the most common type of damage. Lethal damage typically involves internal injuries, either to organs or just large amounts of tissue. It is almost always associated with a loss of blood, and characters who sustain enough Lethal damage to knock them unconscious are usually in danger of bleeding to death. In most cases, there is no meaningful distinction between Lethal and Aggravated damage for mortal human beings; either will kill them just as quickly. Large amounts of Bashing damage may also cause Lethal wounds, usually through internal bleeding.
Levels of Lethal damage are abbreviated to L in combat statistics. Sources of Lethal damage include edged weapons like knives, swords and axes, piercing weapons like arrows and stakes, and firearms. Martial artists may learn to deliver blows which cause Lethal rather than Bashing damage. Many natural hazards, like fire and some sources of electricity, also cause Lethal damage to humans.
Lethal damage causes Lethal wounds, which are marked in the health track using an "X". A character whose health track is full of Lethal wounds and sustains further Lethal damage - assuming they survive - upgrades their existing wounds to Aggravated ones. Lethal wounds heal slowly, usually requiring medical attention if complications are to be avoided. Some supernatural creatures are able to heal Lethal wounds almost instantly, or at least significantly faster than humans. Some - most notably vampires - can not be killed by Lethal damage alone, though it can severely incapacitate them. Many, but not all types of armour protect the wearer from Lethal damage.