Gazelle

s were a type of Earth mammal the Third Doctor and the Brigadier once encountered at a zoo, early in the Third Doctor's life. Normally docile, the wawas attacking its handlers. This odd behaviour made the Doctor and UNIT suspicious of nearby activities. (TVC: The Arkwood Experiments)

The Seventh Doctor and Ace saw s living in the Ngorogoro Crater in 1926. (DWM: Prelude Birthright)