Origin and description
The Mi-go are a subspecies, created by the Old Ones on the planet Yuggoth. They are large, pinkish, fungoid, crustacean-like entities the size of a man.
Where a head would be, they have a 'convoluted ellipsoid' composed of pyramided, fleshy rings and covered in antennae. They are about five feet long, and their crustacean-like bodies bear numerous sets of paired appendages. They possess a pair of membranous bat-like wings for short trips through the air.
The Old Ones send the Mi-go to Earth
Prior to their invasion of Earth, the Old Ones dispatched the Mi-go to Earth to gather intelligence on humanity. The Mi-go set up outposts in remote areas such as Antarctica, Greenland, the hills of Vermont, the Himalayas, the Australian Outback and many other such remote areas, where they wrote logs on Black Stones.
However, the Old Ones could launch their invasion of Earth, however, the White Lighter Elders and The Source Of All Evil united to fight the Old Ones in a long and bloody war. In the end, the Old Ones were defeated and sealed up in an empty dimension.
The Mi-go were thus left on Earth, when the Old Ones were defeated. The Mi-go subsequently went into suspended animation, only waking to defend their outposts when humans got too close.
At some point, all the Mi-go in the Antarctic outpost all died off, leaving the outpost deserted for thousands of years.
As of 2017, only the Greenland and Himalayas outposts are still inhabited by the Mi-go.
Henry Akeley and Albert Wilmarth
The hills of Vermont, location of one of the Mi-go's outposts.
In the 1920's, a man living in the hills of Vermont, Henry Akeley, discovered the black stone of the Mi-go outpost there. He got in touch with a Professor Albert Wilmarth of Miskatonic University, and told Wilmarth about the stone.
However, before Wilmarth could follow up on it, Akeley mysteriously disappeared without a trace, supposedly captured or killed by the Mi-go.
The mystery of his disappearance remains unsolved to this day.
Rex and Hannah encounter the Mi-go for the first time
In 2014, Rex Buckland and Hannah Webster were invited to Vermont by Bill Kline a colleague of Rex’s at Stanford. Kline had found the black stone of the Mi-go, and wanted Rex to translate the writing for him. Rex discovered the connection to the Old Ones, and tried to warn Kline about it. However, Kline mistook Rex’s concerns for professional jealousy, he believed Rex wanted to claim the stone for himself, and refused to cooperate any longer.
That night, Kline was attacked by the Mi-go, who had awakened to protect their stone, and he went insane at the sight of them.
Over the next several days, Rex and Hannah, with the help of Randolph Carter, (this was their first encounter with him) pieced together the story of the Mi-go. Using his copy of the Necronomicon, Rex opened a portal to Yuggoth, in which the Vermont Mi-go used to return to the dark planet.
The Antarctic Outpost
Soon after, Rex and Hannah were again contacted by Randolph and informed that a scientific research base, maintained by Miskatonic University in Antarctica, had made a major discovery. Worried that perhaps the personnel of the base had discovered the Antarctic habitat of the Mi-go, Rex and Hannah traveled there, accompanied by Randolph. They thus discovered remains of the Mi-go, that had had died off thousands of years before. The habitat was currently inhabited by descendants of some followers of Napoleon Bonaparte who had fled France following his defeat in 1812, having ultimately ended up there because of Napoleon acquiring a copy of the Oban Compendium. Rex and Hannah ended up saving the outpost and its inhabitants from certain disaster, although the long term survival of those inhabitants required them to re-establish contact with the outside world.
The Deep Ones
At some point, the Mi-go in the Australian Outback abandoned their habitat on land and adapted themselves to live under the sea. These Mi-go thus became the beings called the Deep Ones. Over time, they interacted and mated with humans, creating human/Mi-go hybrids. The mer-people were a possible offshoot of these hybrids.
The Deep Ones would have a major impact on the town of Innsmouth, Massachusetts (see page on Innsmouth for history).
Rex and Hannah's return to Yuggoth
In early 2016, Rex and Hannah returned to Yuggoth, in search of a cure for an illness that had infected the people of Arkham, Massachusetts.
Soon after, the two former Warlocks encountered the Mi-go. The Mi-go, even though they had recognized Rex and Hannah as the two who had helped them return to Yuggoth, asked the two former Warlocks why they had returned. Rex explained the situation to them, hoping that the Mi-go would feel indebted to the two humans who had helped them get back home. The Mi-go, were indeed grateful that Rex and Hannah had aided in their return to Yuggoth and provided the cure for the illness.
However, the Mi-go then told the two former Warlocks that the debt was now paid in full, and that no further visits to Yuggoth would be tolerated. Rex and Hannah, understanding that the Mi-go meant business, quickly took their leave of the dark planet.
Fort Albert
On June 20th, 1887, British troops, on an expedition to the Himalayas, found a black stone and brought it back to Fort Albert, located in the nearby British Raj. Said stone told the account of the Old One called Hastur, and had been kept by the Mi-go in their Himalayan habitat.
Rex and Hannah, having learned of these events, used the time key to back in time to 1887 to examine the stone. After having confirmed that the stone was Mi-go in origin, Rex and Hannah tried to convince the commander of Fort Albert, Colonel Robert Westphalen that the Mi-go would attack the fort to recover their stone, however, Westphalen refused to believe them.
That night, the Mi-go attacked the fort and the British casualties mounted. Rex and Hannah told Westphalen to pull his men back, that they could not fight the Mi-go. Westphalen was soon forced to agree, but not before twenty-seven of this men were rendered permanently insane by the Mi-go. The Mi-go then recovered their stone and departed the fort.
Upon their return to 2017, Rex and Hannah transcribed the writings from the stone and learned of Hastur for the first time.
References
The Whisperer In Darkness by H.P. Lovecraft
Rex and Hannah Chronicles Story No. 32: The Black Stone
Rex and Hannah Chronicles Story No. 33: The Emperor’s Legacy
Rex and Hannah Chronicles Story No. 38: Innsmouth Revisited
Rex and Hannah Chronicles Story No. 41: Outbreak
Rex and Hannah Chronicles Story No. 45: The Siege Of Fort Albert