Sabre-Toothed Gorilla

Sabre-Toothed Gorillas, (PROSE: A letter from the Master) also spelled as sabre-toothed gorillas, (COMIC: The Sabre-Toothed Gorillas) was a species of aggressive primates native to an unnamed planet, which the Second Doctor once compared to Canada.

History
The Doctor, John and Gillian encountered a tribe of sabre-toothed gorillas, but were rescued by a professor, who had developed a substance he called squidge. The group used weapons made of squidge to hold off the gorillas until they could make their way back to the TARDIS. (COMIC: The Sabre-Toothed Gorillas)

mentioned in an introduction to Doctor Who Magazine that he once did a bit of "charity work" for a group of jobless Earth colonists, where he gave work placements to the colonists in the Sabre-Toothed Gorilla House of the Galactic Zoo, as a part of "humanitarian aid"; however, his definition of humanitarian aid involved the Sabre-Toothed Gorillas eating the colonists, which the Master decided not to speak of in case he brought on the negative attention of the Time Lords. (PROSE: A letter from the Master)