Susan (A Town Called Mercy)
From Tardis Wiki, the free Doctor Who reference
Susan, known to the Preacher as Joshua, was the Preacher's 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, its unknown if he was joking or not. The Doctor rode Susan to find Kahler-Jex's ship. (TV: A Town Called Mercy)