The Garm

The Garm was a formidable humanoid of vaguely canine appearance who lived in the Forbidden Zone in Terminus. Unknown to some, he could speak, and his fearsome appearance concealed a harmless nature.

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Whether or not he had a connection to the mysterious time travelling builders of Terminus remains unknown, though if so, he seems to have outlived the rest of the passengers and crew. (The dead pilot of the Terminus, however, had a near-human appearance.) The Vanir used a box which generated sonic waves to control him. He had great strength and the power to ignore energy weapons fired at him. He healed Nyssa by leaving her a decontamination chamber where radiation could cure her of Lazar's Disease (a rather chancy procedure).

The Garm helped the Doctor by using his great strength to prevent Terminus' engines from re-activating and possibly ending the universe. The Doctor then destroyed the box enslaving the Garm. (DW: Terminus)