Hollow Knights are a type of monster in Portal Knights.
The Hollow Knights are known to be capable of moving through the different islands without requiring portals to do so. How they do that is currently unknown.
It also appears that they have variety (at least one of each element), implying they either get to specialize in certain elements, are born/made with certain elemental affinity, or adapt to their environment.
They are most likely to be under the command of the Hollow King.
The Sun appears to affect them significantly, making them teleport away and disappear.
Hollow Knights spawn in every islands (with exceptions) at night. They have various level and element, usually adjusting to the island's level and biome (there are various exceptions, though). Each type of knights have their own attack pattern, and the players should adapt when fighting them.
When it is daytime, all spawned hollow knights will vanish (not die, they don't drop loot when disappearing even with low health). New Hollow Knights will spawn again when it is nighttime.
Hollow Knights are never listed in the List of Enemies in the player's map.
There are 6 primary Hollow Knights the player will meet:
- Hollow Knight of Thunder
- Hollow Knight of Mist
- Hollow Knight of Frost
- Hollow Knight of Fire
- Hollow Knight Overlord
- Hollow Knight of Stars
There are also various Hollow Knights that'll appear during certain events: