The Stalker From Beyond - It Came Without Warning - A Monster For Your Old School Science Fantasy Campaign

Type: Other 
Armor Class: 6{13}
Hit Dice : 6+4
Attacks: Living Weapon {1d4 per round}, Claws {1d3 per round}
Saving Throw: 11
Special : Move In Shadows As Thief , Head Only Non-Vial Area 
Move:9 
Challenge Level/XP : 6/400

These Others come from beyond the human pale from the deeper depths of the Outer Darkness. They hunt & stalk their prey within any type of environment. Those who summon them simply indicate the target release the monster & brace themselves with good defenses. 

The body count of these beings is impressive for they will stalk & kill any humanoid they can without risking themselves being discovered. They often use abandon mills, or other abandon locations where they can store the bodies of their prey. 

They're main mode of operation is to quietly move in shadows, stalking & hunting their prey until they are within an adventitious position. They use living bio weapons as their man hunting tools. They may hurl these creatures 200 or more yards with little effort. The bio-tools are a living part of the other's body & they seem to have an almost limitless supply of them.
There is speculation that they use other strange biotechnological weaponry that does not conform to any known sane or rational technological scale.
 When first summoned these monsters will communicate telepathically with their hosts but its speculated that they speak many languages but choose not to do so. They disdain all others except their own kind but even their culture is unknown. 
Those collected by these stalkers from the stars are placed within a holding area where the hunter feeds on the corpse nightly taking a bit at a time. There is speculation that those it takes are in a sort of undeath coma suffering every little bit of feeding. 

Gothiaui - Bio Weapons From Beyond 

Gothiaui
Type : Monstrous Animal 
Armor Class: 9{13}
Hit Dice:1d2
Attacks: Bite {deals 1d4 damage per round} 
Saving Throw : 18 
Special: Lethal poison, Causes extreme pain the first round as the bio tentacles sink into the skin delivering a painful but not lethal combination of neutro toxins. 
Move : 13 
Challenge Level/XP: 2/30 

These living bio weapons live within the damned flesh of their master. They are hurled at a target & move with a slow flight covering 200 or more yards. The monster skins its bio tentacles into the target delivering a dose of neutro toxins. The target must save versus poison or simply scream in agony losing 3 rounds of action as the poison pumps into their system. 

The third round the monster begins to chew its victim delivering a combination digestive enzyme/poison/ preservative.
The monster will chew into its prey for 1d4 points of damage per round. The monster holds itself into place with four spider like legs.
The monsters are not especially well armored & may be damaged with a large knife or pried off with a short sword. They will continue to function in the presence of living flesh. They wish to carry out their lethal mission no matter the cost. 

These monsters track prey by a combination of heat, smell, & light psionic ability.
The monster feeds on the flesh of its victim passing nutrients along to its master/host at every opportunity. 

The hunters from beyond summoning spells are only found within the most esoteric books of the damned & demonology. They can't be reasoned with or bargained with. A mage must never get between his prey & the hunters 
They may be found on any world simply hunting, eating, & killing. They are creatures of pure essence & hate of old times. 
The stalker  have been seen in various worlds of the Mutant Future, Carcosa, & even within the Carpathians 
Source !