An invisible stalker is an Invisible stalkers are appropriately named [[invisible monster ]] [[monsters]] found later on in the game. It fights They fight only with its their fists.They can be seen with [[ESP]], but not infravision as their bodies are [[Materials|made of]] mysterious magical vapors. Invisible slayers are a stronger variant of the monster. They have extremely low [[Intelligence]], making them impossible to see even through ESP. 

The * [http://en.wikipedia.org/wiki/Invisible_stalker Invisible Stalker] is a classic Dungeons and Dragons monster. Like the original, IVAN's invisible stalker is also made of mysterious magical vapors. Both of the invisible stalker* Invisible stalkers's dialogue lines are the titles of songs by Tom Waits.