Shotgun guy

The Sergeant (sometimes called the Shotgun guy or Shotgun sergeant) is a marine who has been turned into a zombie during the invasion of the UAC bases. He appears as a bald, muscular man wearing bloodstained, slate-gray clothing, and wields a shotgun.

The Doom instruction manual says:
 * Same as the Former Humans, but much meaner, and tougher. These walking shotguns provide you with a few extra holes if you're not careful!

In the instruction manual he is referred to as a Former Human Sergeant.

The sergeant is first encountered on E1M1: Hangar (Ultra-Violence and Nightmare!) or E1M3: Toxin Refinery (I'm too young to die, Hey, not too rough, and Hurt me plenty).

Combat characteristics
The sergeant attacks by firing his shotgun, which is rather less powerful than the player's shotgun: one round produces three pellets instead of seven, and each pellet inflicts slightly less damage on average. When killed, he drops the shotgun, which contains 4 shells (8 on I'm too young to die and Nightmare!).

Tactical analysis
Due to the horizontal "spread" of shotgun pellets, the sergeant is only a marginally greater threat than the trooper at very long range, but rapidly becomes more dangerous upon closer approach. Most stock levels (and many third-party levels which would imitate them), when they contain sergeants, frequently place them on ledges, behind windows, in alcoves, or around blind corners, with the room's entrance in several lines of sight at once. A player who cannot shoot zombies in the ankle or forehead is a player about to take a regular beating (INFINITY.WAD, on the Ultra-Violence setting, provides ready examples).

A single shotgun round easily kills a sergeant at short range, and usually does so at medium range. Frontal assault on multiple sergeants using a pistol is not recommended.

Unless a large group is present (as with the red key corridor in URMEAT.WAD), the sergeant's participation in monster-monster battles is average at best. Although he survives longer than a trooper and can damage more than one creature with each attack, he also tends to pause noticeably and pace the floor between shots (which, additionally, often places him several strides from his target as he pulls the trigger), and consequently can be defeated by a healthy Imp or Demon in the majority of cases.

The ammo distribution of id Software's maps, like that of Wolfenstein 3D, seems to be most balanced at skill level 3. Playing on Ultra-Violence, especially in Knee-Deep in the Dead or Thy Flesh Consumed, peppers the bestiary with numerous additional sergeants, resulting in numerous additional shotgun pickups which can suddenly double the player's ammo stock.

Appearance statistics
The IWADs contain the following numbers of sergeants: