Susan (A Town Called Mercy)

Susan, known to the Preacher as Joshua, was the Preacher's transgender horse in Mercy, Nevada in 1870. According to the Eleventh Doctor, he preferred the name "Susan" and wanted the Preacher to respect his life choices. The Doctor rode Susan to find Kahler-Jex's ship. (TV: A Town Called Mercy)

Personality
Susan was a mild mannered horse, but, being Western, tended to swear. Only the Eleventh Doctor knew this, however.