This group displays many features of a religious sect. Its members believe in the existence of a complex alien crystal, the Monolith, located somewhere in the center of the Zone. Most stalkers treat Monolith adepts with contempt and consider them as lunatics. From its inception the group strives to block all progress towards the center of the Zone, protecting the Monolith from other stalkers. Rumor has it that the group has a large base deep in the Zone, but its exact location is known only by the members.
― Shadow of Chernobyl PDA description

Monolith soldier's PDA:
A number haunts me, as if it's chasing me from a previous life. I knew it then, when I didn't believe. I remember it now - 342089. It's the code to a door but i do not remember the way to the door.


On the Monolith in dreams:
Brothers, the Monolith summoned me last night and I spoke with it. It was awesome in its greatness, nearly blinding me, but its light filled me with power beyond mere mortal comprehension! I know, I feel its power within us all! Only firm faith can overcome evil. It told me its power can fill only those who have faith. Finally, it revealed to me that our victory is at hand!


A convert in the Black Forest:
Brothers, as we were patrolling the outskirts of the Dark Forest we came upon an unfaithful loner. We did not kill him, seeing as he was already on his way to conversion, although he was still half-way in his animal state... Such is the wisdom of the Monolith: once again it revealed to us the true countenance of our enemies. Now our faith is even stronger! It is at hand, brothers! The victory over the unbelievers is at hand. Soon the Monolith will fulfill our greatest desires! Those who are truly faithful to it will be drawn to it, to its glory, its greatness! We shall abide in its radiance forever!


On the test of faith:
Brothers, the Monolith put my faith to the test, and I nearly strayed from the path. But I withstood! Glory to the Monolith! Its trials strengthen us! We were on our way back from the Dark Valley, and I fell behind. Evil grabbed at the opportunity and started tempting me. And... I doubted. The image of truth became distorted; the enemy whispered into my ear lies about how the Monolith uses us as slaves. But then I realized - it's a trial! I remembered the glory and the splendor of the Monolith. I regained my inner strength and my confidence. Since then I have no fear of any trials and know no doubts. Glory to the Monolith!


On the fighting in the Dark Valley:
I walked in the Dark Valley, a place teeming with unbelievers who haven't seen the power of the Monolith yet. We were on guard duty. The attack came at night. We fought bravely. My brothers stood at their ground as befits true believers, and the Monolith summoned many them that day. But not me. My time had not come yet. My gun was useless and silent. And suddenly the Monolith spoke to me: "You are one of mine, and my power rests with you. Stand strong in your faith and you shall defeat my enemies for my greater glory!" And then I turned into shadow. I bent down and walked around them. Dumb savage spies, they didn't notice a thing. they thought we were dead and were laughing at the empty body shells of our brothers. But i was already behind their backs. And then the power of the Monolith came forth from my hands. And that's how he killed them all. I'm happy to serve you, oh, Light of Perfection!


On those who got to the antennae:
Brothers, did you hear about unbelievers who broke through to the antennae? Fortunately, the Monolith guided us and the brothers picked them off just in time. One was eliminated immediately, the other two ran away. Cowards! They're all cowards! True faith leaves no room for fear! Two managed to escape, but the monolith is wise and omniscient. It would not have let them live without a reason.


S.T.A.L.K.E.R.: Clear Sky dialog:
"Well, a whole faction has gone missing. And it's not like they were taken out by people or wiped out by monsters. They just vanished, warts and all. These guys were weird too, with a real hard-on for the Zone. They believed that the Zone was alive, and in its center was a Monolith - a Wish Granter. So they declared themselves the protectors of this Monolith. And then one fine day their whole faction just got up and took off for the center. Yep, right to the Wish Granter. They headed for the Scorcher, crossed the Barrier, and noone has seen them since."


S.T.A.L.K.E.R.: Clear Sky dialog:
"I heard a whole faction went missing in the Zone. You ever heard of Monolith? Well, they used to protect the Zone from others, but they made a move towards the center right before the emission. Nobody has heard from them since, but recently some real aggressive stalkers have been attacking from where the Scorcher is, killing everyone and asking no questions. I know because I saw them myself around the military warehouses, and I reckon they might be those same Monolithians who disappeared. It wouldn't surprise me, because their uniforms looked real similar."


S.T.A.L.K.E.R.:Call of Pripyat dialog:
Lt. Kirillov: "Yeah, we broke into a Monolith warehouse the other day and it was full of ammo for every type of weapon you get in the Zone. I wonder how they get so much weaponry in here. I'm guessing one of the perimeter guards must be selling it to them..."