Bluebuck

 was a kind of antelope native to Earth which was prized for its distinctive blue coat. The last bluebuck was held in the Museum of the Last Ones until it was stolen by Frank, who sold it off. (PROSE: The Last Dodo)

While trying to convince the Sea Devils to side with him and eradicate humanity, cited the extinction of the bluebuck as an example of humanity's destructive impact. (PROSE: Doctor Who and the Sea-Devils)