AA Battery

AA Battery, also pronounced as Double-A Battery, is an Arabian horse belonging to Cletus Jones. He has never been used in the field and is perpetually confined to the stables.

Trivia

 * AA Battery's name is anachronistic for the 1898 setting, as his namesake was not invented until 1907.
 * This is one of the reasons why some believe Cletus to be a time-traveller.