Stalkers exploring the Zone on their own. Most of stalkers are loners as membership in grouping takes valuable time and thus reducing the income; besides, some are just inclined to isolation and independence.
Representatives of criminal world who came into the Zone for different reasons: earn from selling the artefacts, hide from the law, buy or sell weapons. The Zone has quite a few of this element, ranging from hoodlums to hardened criminals.
Those who suffered extensive impact of radiators in Yantar or some other sectors. Incautious stalkers quickly become insane, turning into walking semi-corpses. They are plentiful in the Zone, some can even reach the perimeter.
Researches of the Zone nature and the nature of its bearings. Under their favourable attitude a lucky stalker can profitably sell the Zone loot to scientists without the dealer’s mediating.
They may move alone or in groups of up to five people. They do not let regular stalkers approach, immediately opening fire.
Anarchists and daredevils who declare themselves to be fighting for free access to the Zone, and consequently find themselves in constant conflict with army units, military stalkers, and Duty.
Most stalkers treat Monolith adepts with contempt, and consider them lunatics.
From its inception the group has attempted to block progress towards the Zone's centre.
Only Duty representatives refuse to trade unique items from the Zone with the outside world. According to rumours, all artifacts found by members of this group are passed to scientists.
The most mysterious group in the Zone, the very existence of which is doubted by many.