Robot Yeti

Robot Yeti are devices created by the Great Intelligence.

Appearance
The Yeti robots were large and hairy to disguise the control spheres that provided their motive power. The sphere was hidden under a flap at the chest. Their hands, feet and eyes where the only parts not covered in fur. The hands and feet were black and bumpy. (DW: The Abominable Snowmen, The Web of Fear)

History
The Yeti serve the Great Intelligence, a disembodied entity from another planet, which tried to form a physical body in order to conquer the Earth. The Yeti are initially a ruse to scare off curiosity seekers, and later form an army serving the Great Intelligence. They are similar in appearance to the real Yeti. (DW: The Abominable Snowmen)

More than thirty years later, dead Robot Yeti, on display, awoke and took over London. (DW: The Web of Fear)

The latter attempt was one of the events which caused the formation of UNIT.

A lone Yeti, left over from Rassilon's game, was found by the Second Doctor and the Brigadier under the Dark Tower. It was maddened by a firework thrown at it by the Doctor, causing a rockfall. (DW: ''The Five Doctors).

Behind the Scenes

 * The date of the second Yeti invasion remains a point of contention for Doctor Who fans, because it brings up the UNIT dating controversy. The perhaps not entirely canonical UNIT website gives the date of the incident as 1968, the same year The Web of Fear aired.
 * The sound effect of a Yeti's roar is created by slowing down the sound of a flushing toilet.