In Speculative Fiction, especially video games, there's a habit of utilizing animals as full-fledged war machines, rather than just mounts or for pulling. This makes a fair bit of sense, especially in Fantasy worlds: If there are three-ton, fire-breathing dinosaurs in your kingdom, sooner or later somebody's gonna get the idea to unleash them on people they don't like. Depending on their intelligence, they may be capable of working independently. See also Dragon Rider, Horse of a Different Color, Weaponized Animal. Examples of Beast of Battle include: