Spider Parasites of Atlach-Nacha

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

Great Race of Yith (New)

In prehistoric Australia, the technologically advanced Yithians were attacked by the Flying Polyps. In order to escape, the Yithians transferred their minds far into the future. Unheroically, they traded places with a race of hive-minded insects, leaving them (undoubtedly confused) in the Yithians' old bodies in the midst of the Flying Polyp war, never to be heard of again.

Great Race of Yith

The Great Race of Yith—also known as Yithians—are a race that swap minds with other races throughout time and space in an effort to learn everything they can about the universe. The most famous of their inhabited forms are the conical beings of Earth's prehistoric past. The swapped mind subsequently inhabits the Yithian's body until they return, jotting down all they know of the home for the Yithians' great libraries.

Inhabitants of Yekub

The worm-like Yekubians send special cubes out into space, and if an intelligent creature finds and looks into the cube, their mind is switched with the Yekubian's for a brief time.  

Travelers

Much like the Shan, Travelers invade a host's brain and take control of them. Unlike the Shan, however, Travelers are physical beings, and enter their victim's body through their mouth. They start off in a larval form (shown below) and mature once inside the host. Unlike the Shan, however, Travelers can't easily vacate their host.

Tomb-Herd

The Tomb-Herd are gelatinous blobs from another dimension that possess special statues upon entering ours so that they can feed. If a statue is unavailable, they can possess a human for the same purpose.

Shan (Insects from Shaggai)

The Insects from Shaggai, also known as Shan, came to Earth many years ago and became stranded due to a component in our atmosphere. They are a highly advanced race which enjoy torturing other races for whatever reason. They can also phase through solid objects, which they use to enter a human's brain to tinker with it.

Nioth-Korghai

Nioth-Korghai appear octopus-like, but are in fact a dark-orange, "bundle of fungoid creepers joined together at one end"—so essentially tentacles without a body.

Ashen Ones

Ashen Ones are magical creations composed of the dust of ground bones.