The Elder Things: The most technologically sophisticated race in the universe. Theyre not flesh and blood, but theyre entirely physical at least. However they are the oldest "natural" sentient life this universe has to offer, theyre simply from another galaxy and evolved in ways completely and horribly alien compared to Earth life. However they themselves, their physiology, follows the laws of our universe, because it's their universe too. However they're so mentally advanced that theyre technology does not follow these rules. They are the creators of the technology that is responsible for every practical working application of "magic" that occurs on the planet Earth. In fact their technology is so advanced it's undistinguishable from magic. They are the ones who, using their magic/technology, set Cthulu into his slumber, to prevent the destruction of Earth, which they were currently using as a base of operations. It was Cthulu's servants, the two oldest lifeforms on Earth, Hydra and Dagon, and their spawn, that constructed a city for their god around him. Besides putting Cthulu on hiatus, before the mysterious end of the Elder Things and discontinuation of operations on their Antartic base, they also left such things as the Elder Sign, and the fearsome servitor race, the Shoggoth on Earth. Shoggoths regenerate endlessly and are essentially protosplasmic blobs capable of growing any organ neccesary: the ultimate slave race that can go anywhere and do anything.

The Great Race of Yith: One of the two "younger" alien races from this universe. Young in the sense of being unbelievably more ancient than Earth, but young compared to the far more advanced Elder Things. The Yith have technology that is not so incomparable to our wildest dreams and science fiction theorizations, albeit designed for their far different physiology. This is because they think fairly simmilar to us. Physically there are still huge differences, but they spawned in an evolution more parallel to us than the Elder Things or the Mi-Go. And more importantly their heavy contact with humanity has enabled them to interact with us without breaking our minds. The most peculiar thing about the Yith is their psychic abilities. They see all of time at once. Not because theyre hyperdimensional beings themselves, but through acute mental evolution. They foresaw their own destruction and to combat became less than physical, "ascending" themselves to at least semi-hyperdimensional statushood in order to seed themselves in the right places and times, possessing other lifeforms to get the job done, in order to set in motion plans to keep the Great Old Ones at bay.

The Mi-Go: Are an alien race that actually hails from the Milky Way Galaxy. Ironic that something from so close could be so horrifically alien. Theyre alien in the way of the xenoforms from the movie Aliens. They evolved and grew in a horrible harsh environment. However it's their minds that are most frightening of all. Despite being physical and from the same corner of infinity as us, were both so alien to each that we each tend to break each other's minds. The Mi-Go, while utterly disturbed by us, are a experimenter race by nature, and they have continued where the Elder Things left off on using Earth for study. Their technology is of greater utility than that of the Yith, but is of the same broad technological level. However all their weapons and battle-armors are biomechanical, as are their ships, and designed to interface directly with their own unique physiology.

The Great Old Ones are hyperdimensional beings. Theyre not from our universe, and thus they are reality-breaking, mindwarping monsters, often considered to be demons or gods.