The Mi-go (sometimes known as Mi-gos in plural) are a race of disturbing alien entities described in the works of H.P. Lovecraft.
Described as large and pink they are a fusion of fungus and crustacean with a number of bizarre adaptations (yet still being more humanoid than a lot of Lovecraftian monsters).
They are neither actively hostile nor friendly towards humanity - being totally amoral in nature, though they are often depicted as somewhat mad scientists by human standards and have a number of gruesome technologies that they have used on humans (both willing and unwilling).
In fact their most famous device is the stuff of nightmares, known as a "brain cylinder", this device allows a human brain to be removed from its body and transferred across great distances in space and time without fear of death and to add to the horror external devices could be attached to this device to allow the brain to see, hear and even speak. However, Mi-Gos see this act as a generosity they display to humans for showing their superior medical knowledge.
They were former worshippers of the Elder Gods but they turned their backs on them and they are currently at war with them, yet this by no means makes them an ally to humanity as they are far too alien to understand such petty things as human frailty or compassion.