The Yeti depicted in Doctor Who, the Surgeon stories and other Doctor Who media, are robots in the long-running British science fiction television series Doctor Who.
They were originally created by Henry Lincoln and Mervyn Haisman, and first appeared in the 1967 serial The Abominable Snowmen, where they encountered the Second Doctor and his companions Jamie and Victoria. They later returned in its sequel The Web of Fear and one returned in 1983 in Doctor Who's twentieth anniversary special The Five Doctors.
The Yeti resemble the cryptozoological creatures also called the Yeti, with an appearance Radio Times has described as "cuddly but ferocious", disguising a small spherical device that provides its motive power. The Yeti serve the Great Intelligence, a disembodied entity from another dimension, which first appeared trying to form a physical body so as to conquer the Earth. Initially the Yeti are a ruse to scare off curiosity seekers, later serving as an army for the Great Intelligence which they continue to do in The Yeti Factor.
Disagreements arose between Lincoln and Haisman with the BBC in 1968 over a serial introducing another new monster, The Dominators, leading to the writers' departure from the series and the retirement of the Yeti as antagonists.
Because the Yeti used to serve the Great Intelligence (even when the Intelligence returns in Series 7 of Doctor Who, the Yeti never appear again) they also appear in the Surgeon stories and usually, whenever a Yeti is around, the Intelligence is not far behind.
However, previous stories including the Intelligence and the Yeti are sketchy but they do make a return in the revived series of the Surgeon stories where it assists the Intelligence in conquering the Earth in the year 2257.
The first appearance of the Yeti is very similar to the awakening of the Yeti that eventually kills Julius Silverstein in The Web of Fear: In this case, when the Surgeon and his sole remaining companion Ghazal Rashidi land in the Greyfriar's Kirkyard, Ghazal is distracted by the sound of beeping which is actually the sound of a Yeti control sphere and it is this beeping that lures Ghazal and indeed the Surgeon to the so called Covenanters Prison.
In the so called prison, the beeping intensifies and as the Yeti awakens it begins to move and advance on the Surgeon and Ghazal, the former of whom narrowly manages to escape its grasp. But the Yeti sends out a signal to other Yetis stationed all over the cemetery which cut off any exits and these Yeti begin to surround the Surgeon and Ghazal preparing to kill them.
But the Yeti at the cemetery come under attack from a group of students who provide a distraction in order to divert the Yeti away from the Surgeon and Ghazal; despite their escape however, the girls' leader calls it the worst escape attempt ever seen. Once the Yeti get too close, the students release more Yeti into the cemetery to act as a diversion and these Yeti are left to fight.
Two more Yetis are later shown guarding another Scottish Kirkyard in the form of the Kirk of the Canongate where they act almost as security guards like the birds in the abandoned story The Puppy and the Peacock. The Yeti guarding these doors, open the doors to the chapel so that Abigail and her group can enter the chapel; however on their journey here, the group have already seen Yetis on the streets attacking innocent civilians.
A large number of Yetis appear in the streets of Edinburgh as the Surgeon accompanied by Hester Cartridge and Kierra Hastings makes his way to the Outlook Tower and along the way, they can be heard singing a discrediting song that is intended to force the Surgeon to retreat from the Tower. However, for all their singing the Surgeon and his accomplices make it to the tower in the end.
Many of the Yetis impregnated with the Human Factor are shown at the Kirk of the Canongate alongside the rest of the resistance when it prepares to launch a final attack on the Camera Obscura while another two Yetis are shown guarding the Intelligence when the Surgeon and Eleanor confront it.
During the final battle between the Great Intelligence and the resistance, many of the Yetis die largely by being thrown off the roof of the Camera Obscura and once the Intelligence is destroyed, every single Yeti collapses regardless of whether they are impregnated with the Human Factor or the Yeti Factor.