“Alien” - from the Alien movies (excluding AVP)
A killing machine. This xenophobic race lives to kill and is well suited for such tasks.
The typical Alien has the following stats:
Strength: 2D+2 / 5D+2 
Dexterity: 2D+1 / 4D+2
Constitution: 2D+1 / 4D+1
Charisma: 1D / 1D+1
Intelligence: 1D+2 / 3D
Perception: 2D / 4D+1
They have a Movement of 14
Damage:
Puncture Mouth: STR+2D
Tail Spike: STR+1
Story Factors:
Acidic Blood: Blood from this creature is acidic enough to rapidly eat through metal. The more metal it eats through, the more diluted the blood becomes, thus making it so the corrosion process finally ceases.
Natural climber: This creature is an excellent climber, able to scale walls and climb in shafts. Consider it as a skill of Climb +3D.
Good swimmer: Not only can these creatures hold their breath for a substantial amount of time (over 30 minutes), but they are also fairly good swimmers. Consider it a skill of Swim +1D
Xenophobic: These creatures hate any and all other life forms and almost ceaselessly hunt others in order to kill them or use them as birth hosts. (See Face Huggers)
Generational Mutations: With different hosts, new alien warriors come with slight mutations, containing attributes similar to those of the host. The alien can pick up a general appearance or even new methods of attacks from the host.