- In the original Doom, he's a nameless marine sent to do grunt work on Mars after an incident over not wanting to kill innocent people on Earth causes him to lash out against his commanding officer. During his dull-as-dirt assignment, it seems the scientists of the Union Aerospace Corporation (UAC) are conducting experiments with teleporters when everything falls to pieces. One of Mars' moons and a UAC outpost, Deimos, completely vanishes into the ether while another, Phobos, is immediately overrun by The Legions of Hell. Everyone is either slaughtered or converted into minions of the invaders. The marine dispatches to Phobos, where he proceeds to clean up the situation as brutally as possible. During his one-man war against the forces of Hell, he discovers what became of Deimos (ended up floating above Hell itself) and then treks down to the surface of Hell to finish the job.When the sequel, Doom II: Hell on Earth, rolls around, the marine had just finished ripping Hell a new one when a distress signal alerts him that the armies that invaded the Mars moon bases have now breached their way to Earth. The humans who are able to escape the genocide decide their only recourse is to escape the planet but their exit route is barricaded by the invaders and obstructed by a force field they set up. The marine is called to break the line of defense and deactivate the force field on behalf of the other humans so they may escape, which he does and remains as the last human on Earth. However, further communication from the escaped humans reveals that the epicenter of the invasion is still on Earth, allowing the marine to finally push back against the invaders. After fighting their forces he decides to cross back into Hell yet again, this time with the intent of making sure they can never invade anywhere ever again. After this trek through Hell, he manages to essentially destroy it, literally leaving no place for the damned to go once they die. Come Doom 64, Earth is finally mopping up from the attacks from the first two games, when something resurrects all the demons on Phobos and Deimos, prompting another assault that ends in the marine storming Hell a third time and apparently wiping demons off the face of Hell completely by killing the Mother Demon.In Doom 3, since it serves as a Continuity Reboot, Doomguy is a whole new marine, who simply happens to have the bad luck of being transferred to the UAC's Mars base the day Betruger unleashes hell upon the planet. Through determination and sheer luck, he manages to stop the invasion and close the portals, trapping Betruger in Hell after slaying Hell's ultimate warrior, the Cyberdemon.In Doom 3: Resurrection of Evil, yet another new marine takes up the mantle of Doomguy, this time a marine exploring Mars as part of an expedition to try and figure out just what Betruger actually did. Discovering a demonic Artefact that Betruger attempts to use to generate a second invasion, he fights his way into Hell and slays Betruger, stopping his plans cold.
- Action Hero: In Original Games.
- Action Survivor: In Doom 3 and Resurection of Evil.
- Badass: Seriously, how is he not one if he practically destroys Hell by the end of the second one.
- Awesome McCoolname: Doomguy. Can't live up to that in badassery.
- Badass Normal: With emphasis on Badass.
- Empowered Badass Normal: When he grabs soul-powered powerups in original games or the Soul Cube in Doom 3.
- Charles Atlas Superpower: There's nothing supernatural behind his Berserk Punch and ability to withstand direct hits from a rocket launcher.
- Like a Badass out of Hell: Three times in the classic series. In the first game he ends up in Hell after discovering where Deimos had teleported to and wanting to teach the demons a lesson on messing with him. He makes it out in one piece but in the second game, he voluntarily returns to Hell and completely wrecks the joint, to the point that he is left to wonder what would become of the evil men in the world when they die. In Doom 64 he kills the Mother Demon and apparently exterminates the demons completely.
- One-Man Army: It's you and every demon that the depths of Hell can throw at you, get to it.
- Bare Your Midriff: At least according to the box art of the first Doom. Male example, courtesy of Clothing Damage.
- Chronic Hero Syndrome: After returning from Hell at the end of the first game, he volunteers to lead the strike force to recapture Earth's last spaceport and evacuate the last surviving humans. Then after that he volunteers to go back into Hell to reverse the invasion.
- Featureless Protagonist: You get to see his features during a few cutscenes in Doom 3, but otherwise, you never see under his helmet, unless you count his classic "Doomguy's face as health indicator".
- Guest Skater: Doomguy is a secret character in the PC version of Tony Hawk's Pro Skater 3, due Gearbox Software being the one who ported the Windows version of the game.
- Heroic Lineage: In the Wolfenstein RPG, it's implied that Doomguy is a descendant of B.J. Blazkowicz.
- Heroic Mime: Never speaks in any of the games.
- No Official Name Given: While he has plenty of fanon names (and a couple arguably canonical), the Doomguy really has no official, cemented name. Romero stated that he wanted the players to feel like THEY were the marine and to invent their own personality.
- I Choose to Stay: At the end of Doom 64, Doomguy decides to stay behind in Hell to make sure he's killed off the demons for good.
- Palette Swap: In multiplayer other marines become this.
- Slasher Smile: Whenever he picks up a new weapon, he gets a very psychotic grin.
- Sociopathic Hero: His narrations in the "cutscenes" and instruction manuals give this impression. Classic series only.
- Space Marine: A non-Super Soldier example.
- Would Not Shoot a Civilian: He may have issues, but he draws the line here. The backstory asserts that he was transferred to Mars because, upon being ordered to fire on a group of civvies by his commanding officer, he responded by beating the man so hard he got put in a body cast. Or possibly killed him, depending on where you look. Classic series only.
Former Human Grunt, Sergeant, and Commando
- These were the soldiers on Mars (and then Earth) who were "conscripted" into the armies of Hell as front line defenders. They are essentially zombies and increase progressively in toughness (Grunts go down in a few shots while Commandos are armed with a chaingun and will take some punishment). Classic series only.
- Everything's Deader with Zombies: They're former Space Marines killed and animated (or possibly possessed) by demons, being used as
- Gatling Good: Former Commando's Weapon of Choice.
- Glass Cannon: Former Commandos.
- The Goomba: These are the most common enemies you'll face, especially in the early levels.
- Hit Scan: The only enemies besides the Spider Mastermind with hitscan weapons, which can make them (Commandos in particular) very annoying to deal with.
- Shotguns Are Just Better: The Sergeant's weapon of choice, to the point his name in the source code is "Shotgun Guy".
- When Hell first breaks loose in Doom 3, the majority of the civilian population are quickly possessed by Demonic spirits and transformed into Zombies. Alone, they're very little threat, due to their lack of agility, but they have a nasty habit of popping up from behind corners.
- Chainsaw Good: Averted. An extremely rare variant with a hunched back and a leather mask shows up in a few spots in the late game that carries one.
- Dead Weight: Fat zombies are a little stronger and do more melee damage than thin ones.
- Everything's Deader with Zombies: They're created by Demonic Possession and arguably Technically Living Zombies (the very first zombie we see is converted straight from a living victim, implying at least some of the others you fight subsequently went straight from alive to zombie without dying first). They have some capacity for tool use, but these basic zombies are slow and stupid.
- Facial Horror: Some zombies come with this, depending on model type; thin zombies can have their lower jaw ripped clean off, whilst fat ones can have their face peeled off, exposing naked skull amidst bloody meat.
- Glass Cannon: They can deal surprising damage (especially the fat ones) but their slow speed and lack of durability cause them to be minimal threats unless they sneak up on you.
- The Goomba: These are the most vanilla enemies you face in the game.
- Zombie Gait: With a few exceptions, most shamble slowly towards you.
- Stands for "Zombie Security", the basic security troops of Mars are also quickly turned to Hell by the demonic spirits. They avert their civilian counterpart's Zombie Gait and attack with whatever weapons they had while alive. Though armor style varies slightly (shotgun-wielders are more likely to have open faced helmets), and weapon loadout varies from pistol to machine rifle to shotgun, they're all equal in strength. They equate to the Zombie Troopers of the classic series.
- Everything's Deader with Zombies: They're a variant of the regular Zombies above created from the former Marines serving security detail on Mars. Unlike their brethren, they display no cannibalistic traits and are fast agile, and smart enough to use projectile weapons and basic tactics.
- Short-Range Shotgun: Averted: the shotgun-wielding variety has a narrow spread on his weapon, allowing him to shoot from far distances.
- Zombie Gait: Averted: these zombies retain their full mobility from life.
- Former elite UAC Marine troops corrupted by demonic energies and mutated into monsters that now serve as Betruger's personal warriors. Dramatically stronger, quicker and tougher than humans, they tend to fight with chainguns or their own bare fists.
- Combat Tentacles: Most Commandos sport a single long tentacle for their right arm, which they use to attack with.
- Everything's Deader with Zombies: They're a particularly different version of the Z-Secs above.
- Gatling Good: Later in the game, you encounter Commandos carrying chainguns.
- Made of Iron: Much, much tougher than the Z-Secs you've fought up until this point, even though they're barechested instead of wearing armor.
- Hell's own soldiers. Monsters who are capable of throwing fireballs, Imps are the lowest level of demon that lead the charge for the forces that follow.
- Doing In the Wizard:
- Played straight in the novels; their fireballs are explained as the imps spitting up globs of a chemical that reacts with oxygen to ignite, which the imps then fling like baseballs of flaming snot.
- Zigzagged in Doom 3; the UAC file explains that the imps are able to create and manipulate globes of coherent plasma, but explains the scientists can't figure out how that's actually possible in the first place.
- Eyes Do Not Belong There: It's subtle, but the Doom 3 and Ro E version of the imp has multiple spidery eyes scattered over its face.
- Fangs Are Evil: Naturally.
- Fireballs: Their primary ranged weapon.
- The Goomba: Your first properly demonic enemy that you encounter, and one you'll see throughout the games.
- Mooks: Hell seems to have a nigh-unlimited supply of Imps; expect to see them more than every other Demon combined.
- Palette Swap: Nightmare Imps in Doom 64, just like the Spectres.
- Red Eyes, Take Warning: In the classic series.
- No Sneak Attacks: Imps have a tendency to helpfully screech and alert you to their presence before attacking.
- Spikes of Villainy: On their shoulders and knees. Classic series only.
- Wall Crawling: In Doom 3 and Ro E, imps often show up by clambering out of vents, climbing up to balconies, crawling down walls or squeezing their way out of gaps in the walls.
Demon (a.k.a. "Pinky") and Spectre
- Hulking brutes that are tinted pink. These guys get in your face as they have no ranged attack but will do some damage. Spectres are versions of Demons that only appear as hazy outlines when encountered. Doom 3 gives an extensive redesign to Demons, but effectively they're the same.
- Attack! Attack! Attack!: All they know how to do is run at you and bite.
- Though often they'll run back and forth erractically to make it hard to hit them.
- Cephalothorax: Their classic design is basically a giant demonic face with arms up near the temples running around on two legs. They do technically have a torso, it's just their oversized head and forward-hunched position makes head and torso indistinguishable when viewed from the front.
- Eyeless Face: Reboot Pinkies are stated as being born with their faces covered in folds of flab and skin, so they have to chew through their own flesh to expose their mouth, which does nothing to reveal their eyes (if they have any).
- Food Chain of Evil: Pinkies won't hesitate to attack and eat other demons in the classic series, especially Imps.
- It was at least proposed in the reboot that Pinkies all have cybernetic legs because the demons cut off their old ones for food.
- Invisibility Cloak: For Spectre.
- Palette Swap: Spectre is this for the Pinky, being the same monster but with an Invisibility Cloak.
- You Don't Look Like You: The reboot version from Doom 3 and Resurrection of Evil is a monstrous, eyeless quadraped that is... well, sort of a cross between a hornless bull and an overweight fanged piglet is reasonably close, only with its rear half chopped off and replaced by comparatively slender cybernetic legs.
- Disembodied horned skulls that are on fire. They can spawn from other enemies and simply fly into you as their only means of attack.
- Expy: In Doom 3 the Lost Soul was redesigned as a floating, hairless human head with a rocket attachment at the back and wide-split jaws. In Resurrection of Evil they brought back the original "flaming horned skull" design and called it the Forgotten One.
- Flaming Skulls: Disembodied ones, at that.
- Ghostly Glide
- Glass Cannon: They can easily kill you, but they explode after 1-2 shots from the shotgun.
- Fragile Speedster: But be careful with your aim; buggers can be tough to hit.
- Your Skull A 'Splode: After being killed. The explosion is merely an effect, though, and won't affect anything near the Lost Soul.
- Floating blobs of red flesh with a single green eye, horns, and a nasty maw. Doom 3 redesigned the Cacodemons to look more like Pain Elementals, but they're similar to the older variety in gameplay.
- Alien Blood: It bleeds red when shot, but its death sprites clearly have it bleeding blue.
- Fireballs: Their spit. In Doom 3 and Ro E, they actually shoot a sort of ball lightning.
- Ghostly Glide
- Mascot Mook
- Slasher Smile / Technically a Smile: Constant one at that.
Baron of Hell & Hell Knight
- Hell's elite. They are hoofed beings that walk upright and have a ram-like head, basically giant Satyrs. The Hell Knights are brown while the Barons are pink and tougher. They throw bolts of green fire and can slash with their hands. The Barons first appear at the end of the first episode of Doom as the final boss. Redesigned in Doom 3 and Ro E into a less Big Red Devil type appearance.
- Alien Blood: They also bleed red when shot, but their death sprites clearly have them bleeding green.
- Though the Barons bleed red in Doom 64.
- Contractual Boss Immunity: Barons and Hell Knights are immune to their own and each other's fireballs (though this is changed in Doom 64.)
- Degraded Boss: From Episode 2 onward.
- Dual Boss: A pair of Barons at the end of Episode 1.
- Eyeless Face: In Doom 3 and Resurrection of Evil, perhaps as a contrast to the multi-eyed Imp.
- King Mook: In Doom 3, Hell Knights are absolutely massive.
- Palette Swap: The Hell Knight is one. Oddly, he uses a separate set of sprites, but is for all other intents and purposes treated as the same entity as the Baron of Hell, just weaker.
- Another floating blob of flesh with a single eye and unpleasant mouth. These guys are brown (unlike Cacodemons, which are red). They can create Lost Souls, which is how they attack. Classic series only.
- A walking skeleton with the ability to fire rockets off its shoulders.
- Dem Bones: With some armor and rocket launchers.
- Homing Projectile: One of the rockets he can launch.
- Really fat demons with fireball cannons for arms.
- Arm Cannon: Two of them.
- Fat Bastard
- Giant Mook
- Kill It with Fire
- Mighty Glacier: Slow, but their durability and damage output can be frightening.
- A smaller version of the Spider Mastermind, they are strange beings mounted on four metallic legs with a plasma gun bolted to the front.
- Brain in a Jar: And by "jar" we mean a cybernetic weapons platform.
- Giant Spider: Not as big as Spider Mastermind, but still quite big.
- Kaleidoscope Eyes: Normally its eyes are blue, but when attacking the eyes turn red.
- Red Eyes, Take Warning: When shooting.
- A being that can revive fallen monsters. Also attacks the player with flames that can erupt underneath the target.
- Always Accurate Attack: Its flame attack will always hit you unless you can put something between it and you to block it from seeing you. Trees or other monsters won't work, for the record - you have to find a wall.
- Boss in Mook Clothing: Has a lot of health, can resurrect fallen enemies, and has a powerful attack that can only be dodged by getting out of his line of sight.
- Evil Laugh: The way he lets you know how much you are screwed.
- Heal It With Fire: The way he resurrects his fellows.
- Kill It with Fire: How he deals with you. The fire doesn't hurt you, it only marks the place for the explosion he'll cause.
- Mook Maker: In Doom 3, instead of resurrecting fallen enemies, he summons more enemies.
- Moral Myopia: Screams "why?!" upon death because he is Hell's "evil healer". He doesn't understand why anyone would want to kill him since he's only doing good by resurrecting his fellow demons. And then burning you to death.
- The final boss of episode 3 of Doom. A gigantic version of the Arachnotrons, it too is a creature mounted upon four titanic metal legs and a chaingun for defense.
- Big Bad: In the plot of the original game.
- Brain in a Jar: And by "jar" we mean a cybernetic weapons platform.
- Contractual Boss Immunity: To splash damage. This effectively gives it nearly 70 percent resistance to rockets.
- Gatling Good
- Giant Spider: A mechanical one, in fact.
- Good News, Bad News: As noted in the Doom II manual, the Spider Mastermind has a souped-up chaingun as its main weapon:
- Monster Is a Mommy: Not actually true, but the manual refers to the Mastermind as the mother of the Arachnotrons.You guess the Arachnotrons had to come from somewhere. Hi, Mom.
- Red Eyes, Take Warning
- Hell's most fearsome creature and the boss of episode 2 of Doom. It is a towering creature with metal legs and a rocket launcher.
- Arm Cannon: A rocket launcher, to make things worse.
- Artificial Limbs: Metal legs and a cannon arm.
- Climax Boss
- Contractual Boss Immunity: Like the Spider Mastermind, to splash damage. This effectively gives it nearly 70 percent resistance to the player's rockets.
- The Dragon: Again, in the first game's story.
- Boss Fountain of Expies
- I'm a Humanitarian: His lair in the original DOOM features several half-eaten Barons of Hell strung up on the walls, the idea being to make you worried about what could possibly be dangerous enough to look at the Barons — who up 'til now were your most prominent Demonic Spider enemy — and think "Dinner!"
- Lightning Bruiser: He's the fastest-moving monster in the game apart from the Archvile and the Lost Soul when it's charging, has 4000 HP and an immunity to splash damage, and can easily splatter an unwary player who's a Fragile Speedster/Glass Cannon by comparison.
- Mascot Mook: Not anywhere near as popular as the Cacodemon, but still the second most recognizable enemy in the game.
- One-Hit Kill: Gains the ability to stomp on the player for an instant kill in Doom 64 (as well as the Brutal Doom mod.)
- Wake-Up Call Boss
Icon of Sin
- The leader of Hell and the final boss of Doom II. Spawns demons to defend itself.
- Attack of the 50-Foot Whatever: All the player ever sees is it's head, but the ending implies that it's massive enough to destroy most of Hell in its death throes.
- Big Bad
- Chekhov's Gunman: Its face shows up on stage architecture in both games before the player even knows about its existence.
- Death by Cameo: The Icon of Sin is actually a big wall with a hole. The actual entity that takes damage is the head of John Romero impaled on a spike.
- Mook Maker
- No Name Given: The Icon of Sin doesn't actually have an official name. The name just comes from the stage it's fought in and is the generally accepted name among the fandom.
- Subliminal Seduction: The sound that plays when he first sees you is backmasked."Oremor nhoj, em llik tsum uoy, emag eht niw ot."
- The final boss of Doom 64. A demon with the ability to resurrect other demons much like the Arch-Vile (only making them stronger than before.) Single-handedly rebuilds the demon army, forcing the marine to put them down another time.
- Big Bad
- Gameplay and Story Segregation: Apparently all she needs to do is pass by a demon and it comes back to life. You fight her in a room likely covered in dead demons (unless you use the Demon Artifacts to seal off the portals before any come through) and they all stay dead.
- Kill It with Fire: Her primary attack
- Monster Is a Mommy: Subverted. It's called the Mother Demon, but according to the story it just resurrects dead demons instead.
- A large monstrosity with the body of a spider with a humanoid torso, similar to a centaur.
- Degraded Boss: Much like the Barons of Hell and even the Cyberdemons of the original games.
- Fan Disservice: The Making of Doom 3 book states she was built with the concept "Sexy + Gross = Creepy".
- Monster Is a Mommy: Possibly. Earlier in the game the player hears "They took my baby" said by a voice similar to the Vagary's.
- Also, given that the Vagary's boss fight takes place at the end of the Alpha Labs, which is literally crawling with the other spider-based enemies, the Trites, there is a popular theory among the fandom that the Trites have established an insect-like colony within the Alpha Labs with the Vagary as their queen.
- If you can spare the time to look at the Vargary's abdomen when fighting her, you'll see it's translucent, with a giant demonic foetus floating inside! It actually looks somewhat similar to the Mancubus.
Guardian of Hell
- A massive blind beast that chases the player through the bowels of Hell.
- Attack Its Weak Point: The Soul Cube even tells you to.
- Cores and Turrets Boss: Half of one; it uses orbiting "Seekers" to compensate for its blindness
Saboath & Sgt. Kelly
- The possessed form of Sgt. Kelly. Most of his body has been replaced with military hardware.
- The final boss of Doom 3. Even bigger than before.
- Contractual Boss Immunity: To everything but the Soul Cube.
- Flunky Boss: He's escorted by a lot of minor demons for you to recharge your Soul Cube with.
- Giant Foot of Stomping: His melee attack, which is a One-Hit Kill.
- Legacy Boss
- Attack Its Weak Point: The Berserk Hunter. Shoot its "heart".
- Burning with Anger: The Berserk Hunter.
- Flash Step: The Helltime Hunter.
- Shielded Core Boss: The Invulnerability Hunter uses four nearby power couplings to recharge his energy shield.
- Shockwave Stomp: One of the Invulnerability Hunter's attacks.
- Tennis Boss: The Helltime Hunter.
- Victor Gains Loser's Powers: After death, their powers are absorbed into the Artifact for the player to use against the next one.
- Warmup Boss: The Helltime Hunter exists mostly to teach the player how to use the Grabber.
Dr. Bertruger & Maledict
- The new leader of Hell, fought at the end of Doom 3: Resurrection of Evil. A giant pterodactyl-like or gargoyle-like demon that spews fire and summons meteor showers.
- Be Careful What You Wish For: In the final cutscene, he demands that the marine gives him the Artifact. The marine shoves the Artifact down the Maledict's throat, killing him almost instantly.
- Draco Lich
- Contractual Boss Immunity: Inverted; his attacks cut through your invulnerability if you try to use the Artifact.
- Final Boss, New Dimension
- Flunky Boss: He likes to summon a lot of Forgotten Ones.
- Heads I Win, Tails You Lose: After his health is depleted, the fight immediately switches to a cutscene where he knocks the player character on his ass.