The Cleaver: The first boss of Dementium: The Ward, this boss is found in Chapter 4 (The Cleaver). It's left hand is a cleaver, and it's right is a needle with a green liquid in it that is used as a ranged attack. The Cleaver is large, and heavy, and has no eyes.

The Wheelchair: What seems to be a deranged veteran with a Gatling gun, who moves around in a wheelchair. He will flee from the player, but fire his gun from a distance. Unlike other bosses, he has a ranged weapon, and will be able to attack you if you are within his sights. The Wheelchair is also officially known as Wheelchair Gunner.

The Maw-Room: Found after the gramophone, this room contains several maw-like patches on the walls, and ceiling. They "Birth" Molluscas.

The Doctor: The final boss of Dementium: The Ward, and the one who is responsible for the whole problem. Seen in both openings, and throughout both games (heard throughout the second). In the battle he will move towards the player, and fire white spheres of light. As the battle continues the player loses vision as the view goes white, meaning William is passing out. The Doctor is also officially known as both "Brain Tweaker", nd "Evil Doctor".

Dementium II

The Gnaw: The Gnaw is the first boss in Dementium II.

Wendigo Witch: The second boss. She has a human-like appearance, but is disfigured, and demon-like. She attacks by charging, shrieking, and she can change her appearance to resemble Williams' wife, Elizabeth.

Gorgamesh: These brutes are enemies that physically resemble the Cleaver, with barbed wire wrapped around the club-like hands, and high resistance towards damage. It first appears in a cutscene as one of them hits a guard, but gets killed by another guard with an assault rifle.

Colossus: Found in Chapter 4 (The Colossus). The biggest enemy of all. It attacks the player after smashing a wall, and proceeds to attack. Only dynamite hurts it. It is a giant blob with a face, and arms with knives for hands.

Malatesta: A huge serpent. It's been mentioned from several papers, and notes, that it originates from the Planes of Anguish. In attempt to kill the player, it will ram into, fall upon, and spit fireballs on you. It is the final boss of Dementium II. It can only be damaged by attacking its gems with ranged weapons.

Enemies

Chestmaws:: Called Freaks in Dementium: The Ward, these are basic enemies, and are seen throughout both games. They resemble horribly disfigured humans. They have a large mouth in their chest, and no eyes, possibly indicating that they guide themselves by sound. There are Normal Chestmaws, and Spitting Chestmaws. They may be found in small rooms or on the floor acting as dead bodies. In Dementium II they have several mechanical prosthetics. Chestmaws are also officially known as Zombies in Dementium II.

Scritters: Insects that crawl around in groups. They can be driven away with the flashlight.

Molluscas: These enemies are slug-like worms that attack in groups of 4 to 6. They move fast, and their baby-like crying sound can be heard. They have a lighter colored counterpart, which do more damage, and have twice as much health as their darker counterparts. The noises they make are similar to a heavily-distorted dolphin.

Banshees: These are found in long hallways. They are nightmarish creatures that resemble disfigured human heads with long gray hair, and long, pointed tongues. They fly back, and fourth, emitting a long, high-pitched scream. The counterparts of these enemies can be distinguished by their black wrinkles, as opposed to the red, and blue wrinkles of the standard version. In Dementium II, they explode after being killed, and can deafen the player. Banshees are also officially known as as "Screamers", and "Mindless Flyers".

Flying Swarm: They fly in swarms, and are attracted to the flashlight. They are scared by any loud noises (gunshots, banging the nightstick on a wall, buzzsaw, etc...)

Dementium: The Ward - Only

Crawlers: They have no legs; but crawl on the floor, and ceiling with their arms. They spit green goo. They will still attack when their heads are shot off. In Remastered, they are completely without skin. Crawlers are also officially known as "Sneaky Torsos".

Dementium II - Only

Guards: They watch over the Bright Dawn Treatment Center. At first they wield Electric Batons and, when the monsters attack the real world, they use assault rifles. When they see William, they will tell him to "drop his weapons", "get on knees", or "that he is in a unauthorized zone". They are voiced by Gregg Hargrove.

Leapers: They hop towards the player to attack with their claws. They are crab-like monsters with no legs, a large mouth, and an open brain.

Lost Souls: These enemies appear in abandoned areas or dark areas. They cannot be killed. If they touch William, they will take him to the Planes of Anguish, in which Chestmaws must be fought. The Shadows must be avoided. The Relic weapon can be used as a shield against them.

Frostbite: Exclusive to the HD "Demake" of Dementium II, they act the same as Lost Souls. They can be killed with a Flamethrower, but will respawn momentarily. They harm the player directly, instead of transporting them.

Aerial Hunters: The flying hunters have a buzz-saw on their tail, which they use to attack when they come close. They explode once they are killed, and can release Molluscas.

Spitters: Fat slightly hog-like creatures that shoot goo. When attacked they roll out of the way and laugh devilishly.

Wailers: Similar to the Banshees, but they cry and stay in a single place until they see the player. They can either follow the player, or spit a black substance that blocks the view.

Slime Mines: They float around in the air and explode (which deals heavy damage if the player stands too close) when contacted or attacked.

ReAnimators: These fungal creatures can revive themselves after killed. The flamethrower is the only way to completely destroy them.

Cut Enemies Dementium: The Ward

Feast Beast: A thin, fast, starving monster that will climb walls, crawl on ceilings, and eviscerate to get its meal. It was supposed to make its debut in Dementium: The Ward, but was dropped due to time constraints. Later on in development, attempts were made to restore it to the game using the AI of The Cleaver, but the results were unsatisfactory, and it was cut once again.

Mindless Wanderers: Emaciated corpses tied together, these enemies were the first completed for Dementium: The Ward. They were cut midway through development in favor of the Chestmaw, as they were deemed "Not scary enough"

Dementium II

Hell Guard: Guards corrupted by the Plains of Anguish, these monstrosities were originally meant to appear late in Dementium II, but were dropped due to budget cuts from Southpeak.

Priapic: Originally meant as the boss for the Pelf Village Church, he was dropped and replaced with the Wendigo Witch due to budget cuts from Southpeak."