Bittenmane
Bittenmane was a male horse that belonged to Attila the Hun. While fighting the Roman Empire in Gaul Attila was cut off from his men with Bittenmane. There, Bittenmane and Attila encountered the Thirteenth Doctor, who was travelling with her companions Ryan Sinclair, Yasmin Khan and Graham O'Brien. Attila did not care greatly for Bittenmane's life as he was merely one of thousands of horses belonging to the powerful war lord.
Bittenmane was killed by the Tenctrama when they began to absorb life energy from the life forms they had spent the last thousand years preparing. However, as the Doctor had previously treated Bittenmane with alien healing gel, the alien healing technology disrupted the Tenctrama's energy matrix as they absorbed Bittenmane's life-force, giving the Doctor time to modify their equipment to drain energy from them rather than from Earth. (PROSE: Combat Magicks)