Robot Yeti

The Yeti Robots were a type of robot created by the Great Intelligence to impersonate real Yetis.They have appeared in the second doctor stories The Abominable Snowmen, and the The Web of Fear''. They made an appearence in The five Doctors and are notable for a being a populaur monster even though there first two stories are incomplete. There has been has been various suggestions that the yeti should be revived for the new series. This seems unlikley as Rusell T Dsvies said he will not bring back the ice warriors and the ice warriors are more likley at being revived than the yeti. although resembling the cryptozoological creatures also called the Yeti, are in actuality alien robots. Their external appearance, that of a huge hairy biped, disguises a small spherical mechanism that provides its motive power. 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.

The Great Intelligence and its Yeti minions were thwarted twice by the Doctor's second incarnation, played by Patrick Troughton, in the serials The Abominable Snowmen and The Web of Fear. A Yeti was also one of the creatures in the Death Zone featured in The Five Doctors.

The sound effect of a Yeti's roar is created by slowing down the sound of a flushing toilet.

Appearance
The Yeti robots were large and hairy, to disguise the control spheres that provided their motive power. (DW: The Abominable Snowmen, The Web of Fear)

History
The Yeti were originally designed by the Great Intelligence in the guise of real Yeti, in 1935 Tibet. (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 the UNIT. (unit.org.uk)

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.