Spider Parasites of Atlach-Nacha

 Atlach-Nacha sends out spider-like creatures which can take over the mind of others.

Spawn of Yig

The Spawn of Yig are the offspring of Yig and a human, and take on the characteristics of both parents. Skin is scaly and coloured similarly to that of a snake, while limbs are shrunken and dangle uselessly from the body. The face is partially human, but the eyes are cold and lidless.

Servants of Y'golonac

Small, deformed, and eyeless, the Servants of Y'golonac dwell with him in darkness behind a great wall. Like him, they also have sharp-toothed mouths on their palms.

Beings from Xiclotl

The Beings of Xiclotl look like 16-foot high metallic trees, and are enslaved by the Shan as brute labourers.

Mutated Voormis

Mutated Voormis—previously known as Trolls—are larger and more animalistic than their ancestors.

Vile Fungus

The Vile Fungus appears to be a mass of regular mushrooms from a glance, yet they can cast out tendrils that can infect those they touch. The victim is then progressively overcome by the fungus until they are unable to move and the cycle starts over.

Brood of Ubbo-Sathla

The Brood of Ubbo-Sathla are similar in appearance to giant versions of protozoans and other single-celled creatures. Like the Spawn of Abhoth, they are constantly being birthed, and though some are re-absorbed, many do escape. Generally encountered only in Ubbo-Sathla’s primal grotto, no two spawn are exactly alike.

Shoggoths

Shoggoths are possibly Lovecraft's most popular non-deity monsters. They have amorphous forms and are nigh on unkillable.

Shantaks

Like Byakhee, Shantaks are typically treated as mounts. Unlike the Byakhee, however, Shantaks are not very intelligent, so are more suited to the role. Also like Byakhee, Shantaks can fly through space. They are described as being larger than an elephant with a head like a horse's. Despite also being referred to as a "Shantak-bird", they have scales instead of feathers.

Reanimates

Reanimates are an entirely new creation for Call of Cthulhu. Being based off an original Lovecraft story—Re-Animator—I'm surprised their inclusion took this long. For those unfamiliar with the story (or the popular movie), they are basically zombies, created using a chemical reagent concocted by Herbert West. The longer the corpse was originally dead, the more bestial the Reanimate, driving West to always search for fresher and fresher corpses.

Rat People

Once human, Rat People have degenerated to a near animal state. I get the impression from their write-up in the old Malleus Monstrorum that they are even less human than those pictured below, as it says that they sometimes walk on all fours and has no mention of weapons or even clothing.

Nightgaunts

Nightgaunts are native to the Dreamlands, though are regularly encountered in the Waking World. They are faceless humanoids with bat-wings that have a penchant for picking up their victims and carrying them away, all the while tickling them.

Miri Nigri

The Miri Nigri are mute dwarves created by Chaugnar Faugn from the flesh of toads. They tirelessly serve Chaugnar Faugn in his lair, only leaving twice a year to acquire sacrificial victims.

Martense Kin

The Martense family, through generations of inbreeding, degenerated into animalistic monsters. They left the surface world to dwell underground in labyrinthine warrens, shunning the light—though it doesn't actually hurt them.

Hell Leech

While not identical, it seems that Hell Leeches are a reworking of Watchers from the old Malleus Monstrorum. They are both giant leech-like creatures that dwell in murky lakes and rivers. Unlike the image below (it was the closest representation I could find), they both also have tentacles extending from near their mouths and both have paralysing poison.

Gyaa-Yothn

Gyaa-Yothn are said to be related to—and are possibly just domesticated—Ghasts, though they have a horn protruding from their head and are covered in fur. They are ridden by the people of K'n-yan, as well as being used as beasts of burden.

Gn’icht’Tyaacht

The Gn’icht’Tyaacht are tree spirits native to the jungles of West Africa, and are only able to leave their Nuwanda Trees at night. They are seven-foot tall, lanky humanoids with long pointed heads. They also have huge claws and prominent, sharply pointed teeth.

Ghasts

Ghasts are repulsive beings which shun the light. They leap on long hind legs and have yellowish red eyes. Ghasts have an excellent sense of smell and their face is curiously human despite the absence of a nose, a forehead, and other particulars. They speak in coughing gutturals.

Dimensional Shamblers

Little is known about Dimensional Shamblers, save for their hide being described as "not wholly ape and not wholly insect", and their ability to walk between dimensions.

Dholes

Dholes are basically giant worms. And I do mean giant. They are the largest creature in the Malleus Monstrorum, including deities. It's said that there are none on Earth, which can only be a good thing, because they burrow through the ground, infesting the entire planet until it is destroyed.