Marked men

Marked men are those with a unique form of pseudo-ghoulification seen only in the Divide and are only kept alive and in agony from the residual radiation in the Divide, in 2281.

Background
Marked men are the remnants of New California Republic soldiers and Legion stationed at the Divide. The violent storms caused by the Courier's delivery of the Navarro package to the Divide skinned them alive while the intense radiation caused them to undergo a type of ghoulification. This strangely kept them alive, yet in excruciating pain from their flayed flesh. Such injuries and radiation would have killed ordinary ghouls. The marked men are only kept alive by the radiation of the Divide, which now heals their bodies. Rumors of Marked men spread throughout the west coast wasteland similar to the legends of the Sierra Madre and Big Empty.

Despite belonging to completely different factions with opposing ideologies when they were humans, the pain united the men into a single group. According to Ulysses, "radiation's marked them, made them equal in history's eyes." Their hate for both the NCR and Legion's abandonment was turned against the Divide and its intruders. Some former legionaries crafted crude versions of Legate Lanius' helmet, constructed from Divide metal, not with care and strength, but with hate, keeping them anchored. Others shaped crude blades like distant mirrors of their new and unknown Legate, like a symbol they can hold on to, while the Divide tears them. The NCR, on the other hand, stuck to their guns; ranged death from afar being their own symbol. They continue to wear old NCR and Legion armor that has been damaged over time and then patched together with road signs, license plates and other scrap metal.

Biology
 Marked men are a unique subtype of ghoul with a fiery red tone due to their brutal environment; ghoulification made their flesh weak and fragile, but it was the storms that peeled their skin off, leaving behind only muscle. According to Ulysses, the radiation of the Divide may be the only thing keeping them alive. They congregate in squads and small camps of around four marked men and wear ramshackle faction armor. They appear to have resorted to cannibalism to survive within the Divide. 

Gameplay attributes
Marked men level with the player and have a high amount of health for humanoid opponents. In addition, their tattered armor still offers them modest-to-moderate protection (albeit far less than properly maintained regular versions of their armor). They are overall on par with the White Legs tribals of Zion Canyon or the lobotomites of Big MT in terms of health and armor.

They carry a variety of powerful high end weaponry both of the ranged and melee variety, and at higher levels (above level 40) have the unique attribute of being the only faction that almost universally uses non-standard ammunition for their weapons (slugs and armor piercing rounds in particular) which makes them all the more dangerous. Additionally, many marked men make simultaneous use of both firearms and grenades. They also sometimes carry and use Stealth Boys, especially in Ashton.

When inside pockets of radiation, they rapidly regenerate their health (even more so than normal ghouls do), making hit and run tactics far less useful when fighting them in an irradiated area (marked men sometimes regenerate health even when in a non-radioactive area, such as during the final battle in Ulysses' temple). However, they tend to be few in number and it is rare to find more than six in any particular location.

Marked men hunter
Marked men hunters appear to be former NCR troopers, and are exclusively equipped with powerful ranged weapons. They often carry arc welders or tri-beam laser rifles. They also carry trail carbines, assault carbines, or sniper rifles at low levels (level 1 to level 30), and anti-materiel rifles, brush guns, or Marksman carbines at higher levels (level 30 or above).

They overwhelmingly wear former NCR armor (the marked trooper armor), although they occasionally wear the former Legion marked scout armor instead.

Within the game files exists a unused marked man hunter, a glitchy skeleton variant, similar to the ones unused in Old World Blues.

Marked men marauder
Marked men maurauders are higher-ranking marked men that specialize in heavy weapons. They carry missile launchers and light machine guns at lower levels (below level 30), miniguns, heavy incinerators, Gatling lasers, and plasma casters at higher levels (above level 30), and shoulder mounted machine guns at all levels.

They wear either marked tribal armor or marked patrol armor, suggesting that they are a mix of former NCR Rangers and former high-ranking legionaries. As such, they are slightly better armored than the other marked men variants.

Marked men ravager
Marked men ravagers appear to be former legionaries, and specialize in melee weapons. They often carry the Blade of the West, as well as fire axes and shishkebabs at lower levels (below level 30), and sledgehammers, super sledges, and thermic lances at higher levels (above level 30). They also carry and use incendiary grenades.

Ravagers overwhelmingly wear ex-Legion marked scout armor, although they occasionally wear ex-NCR marked trooper armor instead.

Marked men scout
Marked men scouts appear to be former legionaries equipped with both firearms and frag grenades. They generally carry either pistols, one-handed submachine guns, or shotguns. They are equipped with flare guns and Plasma Defenders at all levels, and 12.7mm pistols, hunting shotguns, and hunting revolvers at lower levels (below level 30), as well as 12.7mm submachine guns and riot shotguns at higher levels (above level 30).

Scouts overwhelmingly wear ex-Legion marked scout armor, although they occasionally wear ex-NCR marked trooper armor instead.

Irradiated marked men hunter
Irradiated marked men hunters are marked men that have been irradiated from the missile launched by the Courier during The Launch. They are significantly stronger and will constantly regain hit points, due to them being in a constant radiation bath within the Courier's Mile.

Irradiated marked men marauder
Irradiated marked men marauders are marked men that have been irradiated from the missile launched by the Courier during The Launch. These marauders are significantly more dangerous than standard marauders because while they will rapidly regain health due to the Courier's Mile being a radiation trap, they also carry very large and very damaging weapons.

Irradiated marked men ravager
Irradiated marked men ravangers are marked men that have been irradiated from the missile launched by the Courier during The Launch. These ravagers use their natural ability to regain health in the green glow of the Courier's Mile to rush the player with their melee weapons while other marked men in their unit attack from afar.

Irradiated marked men scout
Irradiated marked men scouts are marked men that have been irradiated from the missile launched by the Courier during The Launch. These scouts still keep their distance when engaging in battle, but after being hurt, they will retreat to cover where they use the intense radiation of the Courier's Mile to heal themselves.

Notable marked men

 * Blister
 * Beast
 * Bonesaw
 * Blade
 * Gaius Magnus
 * Colonel Royez

Appearances
Marked men were originally mentioned in the Fallout: New Vegas add-on Dead Money and finally appeared in Lonesome Road.

Behind the scenes
Marked men seem to have been inspired by the first ghoul concept for Fallout named "blood man".