Osumaran

Osumarans were the natives of the planet Osumare in the Orion molecular cloud cluster. Although they resembled horses, Osumarans were far more intelligent and capable of speech. They used Q7 starships. 19th century Earth was considered to be barbaric compared to their culture. (COMIC: From the Horse's Mouth) They were aware of the Mkali. (COMIC: Fear Buds)

In 1899, an Osumaran named Jata crashed his starship in Wyoming. His ship was too damaged to be repaired, so for three months he masqueraded as the horse of an outlaw named Clint Currie. The Twelfth Doctor learned of Jata, so he bought a white horse and painted a black star on its forehead. He then befriended Jata and replaced him with the horse. The Doctor took Jata back to Osumare in his TARDIS. (COMIC: From the Horse's Mouth)