Plot Armor

"Plot armor" is an informal term referring to a character's unusual ability to survive, due to their importance to the story.

In the Call of Duty series, this can be seen when certain NPCs shrug off machine gun fire, grenade blasts, and other normally fatal events. Commanding officers directly in charge of the player character tend to have plot armor throughout the game, while other plot-critical characters may lose their "armor" once their role has been fulfilled.

Characters without plot armor can die from any fatal event, including accidental death at the hands of the player.

If the player deliberately fires upon such NPCs, play will cease with the normal "Friendly fire is not tolerated" message. However, enemies can fire all they want, to no effect.

Call of Duty

 * At one point during "Ste. Mere-Eglise- Day", Martin's squad is pinned down by Tiger tanks. Sgt. Moody is still visible to the enemy despite taking cover, and is repeatedly shot at by the second tank's machine gun.
 * One glaring exception to the "commander rule" is Captain Price during the events aboard the Tirpitz. Once Evans leaves Price to set explosive charges, Price is scripted to die while defending the entrance.

Call of Duty: Modern Warfare 2

 * During the events of No Russian, Makarov not only has plot armor, but is also capable of shooting through any obstacle when necessary.