- Daniel Gimmer (Tormentor667)
- Nick Baker (NiGHTMARE)
- Fraser Low (TheDarkArchon)
- Michael Niggel (Risen)
- Christoph Oelckers (Graf Zahl)
- Björn Ostmann (Vader)
- Ryan Turner (BioHazard)
- Pawel Zarczynski (NMN)
- Jan Cholasta (Grubber)
- Andrew Fernie (Ninja of Doom)
- Randy Heit
- Lexus Alyus
- Kate Stone
- Travis Miller (solarsnowfall)
- Patrick Niggel (MrMan)
- Scuba Steve
- Nigel Rowand (Enjay)
- Jacob Zuchowski (Ellmo)
Knee-Deep in ZDoom is a reinterpretation of the original id Software's Knee-Deep in the Dead. The idea was to expand the original levels utilizing the power of Randy Heit's ZDoom port, which adds features which are not possible under the original Doom engine. The levels have an atmosphere and design similar to Quake 2, with large, techy bases and similar ambient sounds.
Relive the fear. Relive the nightmare. Relive Phobos.
- Z1M1: Hangar
- Z1M2: Nuclear Plant
- Z1M3: Toxin Refinery
- Z1M4: Command Control
- Z1M5: Phobos Lab
- Z1M6: Central Processing
- Z1M7: Computer Station
- Z1M8: Phobos Anomaly
- Z1M9: Military Base
- Z1M10: Penultimate Evil
- Blood Demon
- A darker variant of the pinky demon with cybernetic enhancements and 300 hit points. Killing them causes their right arm to fall off.
- These are mostly equivalent to the chaingunners from Doom 2 but with a new sprite set and a slightly more animated death sequence.
- Chainsaw Zombie
- A chainsaw-wielding zombie in a brown suit, with 30 hit points. Drops a chainsaw when killed.
- Dark Imp
- There are three variants of the Dark Imp, all of which have black skin and more hit points than regular Imps.
- The first variant looks like a regular Imp with black skin, yellow eyes and large fangs. They will fire blue homing balls of energy, and have 120 hit points.
- The second variant has thin, red eyes and skinny limbs, and 110 hit points. Its behavior is based off the Dark Imps from Skulltag, as it attacks with fast, blue balls of energy. Its death animation is slightly different to the regular Imps.
- The third variant has sunken, orange eyes, a wide mouth with many visible teeth and 130 hit points. Its behavior bears a resemblance to that of the Dark Imps from Mike "Cyb" Watson's Void, which are basically reskinned undead warriors. They will shoot blue balls of energy and also pink balls of energy that leave trails and do more damage. This variant also has an entirely unique death animation.
- Demon Cube
- A spinning cube with a demonic face on the sides, inspired by the guardian cubes from Demon Eclipse which themselves were monster versions of the spawn cubes. They shoot streams of small fireballs. 50 hit points.
- Hell Knight
- These are simply Hell knights from Doom 2 but with a new sprite set. They are now light-brown colored barons.
- Hell's Fury
- Grey-skinned and grey-legged Hell nobles with a head that resembles the Lost Soul from Doom 0.4. They have two methods of attack: either hurling a highly-damaging red baron projectile or shooting homing yellow skulls out of the sides of their head.
- Hell Warrior
- Orange-skinned, tan-legged Hell nobles with lion manes, 400 hit points, and a shield that bears a resemblance to the floating eye symbol. They fling yellow Baron projectiles, and occasionally defend themselves with their shield when they are hurt, temporarily becoming invulnerable. They may also fire a green ripping projectile from their shield. Killing them causes them to drop their shield (which you cannot pick up).
- Mauler Demon
- A dark red variant of the demon with Pain Elemental horns and a damaging charge attack and 150 hit points.
- These Imp-like creatures appear totally invisible until they get up close, then they start clawing at you, and only then can they be hurt. They have 100 hit points.
- Rapid-Fire Trooper
- A zombieman with a rapid fire gun. They drop pistol clips when they are killed. 30 hit points.
- Rifle Zombie
- A shotgun guy-like zombie with brown stains on his armor. They shoot slow-moving bullets (that is, slow compared to hitscans) and drop rifles when they are killed. 40 hit points.
- Rocket Guy
- A zombieman with a rocket launcher. Their low health (50 hit points) and powerful weaponry makes it easy for them to kill themselves and other nearby monsters.
- A small Hell noble with a goat-like head and dark brown skin and legs. They have 400 hit points and a powerful melee attack but no projectile attacks.
- An Imp-like creature with a slouched posture, translucent grey skin, and large red eyes. It moves quickly, leaving a motion blur behind it. When it sights its target, it will stay positioned, hurling red balls of energy towards the target, until it is shot or until its target leaves its line of sight. Its behavior seems to be based off that of the Level 2 Imps from STRAIN. It has 80 hit points.
- Soul Harvester
- A spiky, grey-skinned, emaciated Imp-like creature with 100 hit points. Similar to Heretic's nitrogolems, they shoot yellow homing skull projectiles at their target (the same projectiles as those used by Hell's Fury). Killing them causes a yellow spirit to rise from their corpse as their bodies deteriorate into skeletons.
- Stone Imp
- A variant of Imp made from stone. It doesn't bleed, has 180 hit points, a powerful melee attack, no projectile attacks. When it dies it splits and half and the legs fall backwards and the top falls forwards.
- Bruiser demon
- Named after the bruiser brothers, and the penultimate boss of the game with 3000 hit points. They are dark orange-skinned, black-legged, with glowing red eyes, black horns on their upper body, and have three methods of attack: (1) a large, powerful, trailing fireball, (2) a volley of seven to fourteen smaller fireballs, and (3) a floor-hugging barrage of exploding fire similar to that of the Maulotaur.
- A massive, devil-like entity with two sets of arms (hence the "mantis" in its name). It rises out of a pool of lava immediately in front of the portal to the Shores of Hell, and creates red, swirling pools of energy above its head that shoot projectiles at its target, or spawn Lost Souls. It will also spawn Imps around the pool of lava. It has 15000 hit points (five times that of a Spider Mastermind) so the player is provided with a health bar to keep track of its remaining health.
- Super Shotgun
- KDiZD Grenade Launcher