The Bull Alien is spawned from cattle hosts and has two horns on its head, and is very quick (able to outrun Stinger XT-37s) and powerful. This large Xenomorph variant can knock down military vehicles by rushing in. It is also very durable, capable of taking a rocket to the face without even flinching. Only fire seems to kill them.
Bull Aliens commonly operate in herds, another trait they inherit from their host.
The bull alien has a similar demenour to both the Rhino Alien and the Crusher, due to the fact that they are all quadrupedal, extremely aggressive and use their large heads to ram their opponents.