Buffalo

Buffalo were cattle-like creatures that lived on Earth. Because Roz Forrester's family name, Inyathi, translated as "buffalo", she wasn't allowed to eat a buffalo. (PROSE: )

History
Buffalo were once the dominant species on Earth, but when their Herd-Leader was trapped in ice they degenerated without his mind. The Bovine Herd Leader revived thousands of years later and was able to travel back in time. He found his species were being wiped out by the Native Americans and guided Christopher Columbus to America in 1492, hoping the Europeans would wipe out the Native Americans and save his herd. However, the Europeans wiped out the buffalo themselves. (AUDIO: )

The Seventh Doctor and Ace saw buffalo living in the Ngorogoro Crater in 1926. (PROSE: )

The last buffalo died in captivity in 2193. (PROSE: )

Cultural references to buffalo
The Sixth Doctor used the password "buffalo" to access the UNIT telephone line. (AUDIO: ) The Ninth Doctor later told Mickey Smith to use same password to access a variety of areas of the UNIT website, (TV: ) which he shared within a couple of days to the readers of his website, along with another password, "bison". (PROSE: )

At different points, "bison", "buffalo", (PROSE:, Secure Login) and "badwolf" were passwords to the operations board on the UNIT website. (PROSE: Secure Login) The password "buffalo", if entered into the override code field, allowed an individual to navigate and fire a missile towards anywhere on Earth. (GAME: )

Behind the scenes

 * The DWU fails to use buffalo as a synonym for bison — which it is, in a limited sense. Certainly, North American buffalo are bison. However, the kind the Seventh Doctor and Ace saw in Africa would have been and not at all bison.
 * However, the U.N.I.T. tie-in website does use the password "buffalo" and "bison" interchangeably.