Stalkers are a race brought to Gielinor from another realm by the Mahjarrat Bilrach, led by World-gorger Shukarhazh. They resemble horrifying beasts with gigantic eyes or clusters of eyes, and often have numerous appendages. Stalkers are very intelligent creatures which possess great control over magic, to which they also have a high resistance. If needed, stalkers are also able to engage in conversations with humans in the human language; they do this because their own language is physically harmful to humans when heard. Bilrach summoned the stalkers, among many other races such as the savage behemoths, in order to guard the floors of Daemonheim as he was progressing.
Most Stalkers have the ability to levitate like Plane-freezer Lakhrahnaz. Some Stalkers prefer to rest on the ground rather than floating continuously, one example being Night-gazer Khighorahk. Others prefer places where they can suspend themselves in the air with their tentacles (Shadow-forger Ihlakhizan). Finally, Flesh-spoiler Haasghenahk's second form balances itself (though it cannot move) on its spinal cord. All crucial body functions are within a Stalker's eyeball, allowing them to undergo this trauma.
Stalkers tend to build nests, mainly used for growing and resting, but also for spawning. Some of them grow to large proportions, notably Night-gazer Khighorahk, who is about twenty times the size of a human. Some have special powers, of which Plane-freezer Lakhrahnaz is an example. This stalker can control temperatures, similar to To'Kash the Bloodchiller. Shadow-forger Ihlakhizan has control over light and shadows. Like Khighorahk, Flesh-spoiler Haasghenahk also has two forms. He can also spawn Flesh-spoiler spawns to aid him during his second form. The manner in which he fights is exceptional; he shoots his biggest eyeball out of his body and then retracts it.
Reproduction behaviour of the stalkers varies, albeit they all do so asexually, either by budding or spawning offspring in what seems to be a genderless form of parthenogenesis. Their offspring grow around the exterior of their parent's body, until maturity. Some of the baby stalkers (like those which originate from Night-gazer Khighorahk) appear as an optic nerve on the exterior of the stalker parent, which crawls out of its parent and takes residence in a nest. Others, like those which originate from Flesh-spoiler Haasghenahk grow inside their parent until the parent bursts, and the offspring crawl out. According to the sneakerpeeper, stalkers have a maturing ritual. When spawning, the spawn have to be kept wet with ooze from the eyeball to avoid them drying out and dying.
According to the Sneakerpeeper, Stalkers have a hive-mind.
Some stalkers are able to extend their bodies through the mind, such as World-gorger Shukarhazh. This stalker in particular can immunise itself by setting wall-eyes into it's chamber. It is then immune to all kinds of attacks. When it's wall eye is being attacked, it will shift back to its body, being vulnerable for a moment. Then it shifts again, making weapons less effective than before.
Apart from the five bosses, there are two more species of attackable Stalkers within Daemonheim. The Seeker requires level 71 Slayer to kill and a Soulgazer requires 99 Slayer, and are fairly rare encounters.
- Plane-freezer Lakhrahnaz
- Night-gazer Khighorahk
- Shadow-forger Ihlakhizan
- Flesh-spoiler Haasghenahk
- World-gorger Shukarhazh
- The Stalker language is harmful to humans if heard; this is similar to how the language of the Mahjarrat drives humans mad if they hear it.
- The Sneakerpeeper is the only friendly Stalker, and also the only one outside of Daemonheim.
- Stalkers appear to be based on Beholders from Dungeons and Dragons.
- After the Player Owned Port update on 7 jan 2014, a new "island" appeared on the map "seeker's synapse" which apparantly is an island sized creature with a brain in the middle, filled with seekers.