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.
They may move alone or in groups of up to five people. They do not let regular stalkers approach, immediately opening fire.
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.