Xenomorph caste 3: Runner

While not a much loved Alien movie Alien3 for me is still pretty awesome and one of the elements which made it so was the introduction of the Runner xenomorph (The term Dog Alien was dropped buy many fans with the revelation of the alternate cut). Alien3 showed us that the xeno would take on elements of what ever creature it facehugged. In Alien3 a Dog/Ox depending on which cut you watched.
As a result the beast chose a quadrupedal stance over two legs as its legs were longer then a human spawned xeno. It also lack dorsal horns and seemed to prefer to kill the convicts on sight( although this could have been it protecting the unborn queen Ripley was carrying) One could also speculate that because of a more basic host it do's not have the smarts to harvest the convicts for the maturing queen.

The beast could reach powerful levels of speed equal to a jungle cat be it walking on any surface. The "Dragon" as Golic called it has the highest kill count of one single Alien in any of the movies.

The creature would turn up in a number of games and be one of the more unique foes with its speed and agility.

Featured in

Alien3

Alien Trilogy(PS1)

Aliens vs Pradator 2(pc)
Aliens vs Predator Extinction (Xbox/PS2)

Aliens vs Predator 2010 (xbox360/PS3)