Other players or certain NPCs that invade your world.
In addition to human-controlled invaders, there are a number of NPC Black Phantoms that are scripted to automatically invade the player when the player approaches certain areas of the game. NPC Black Phantoms only spawn if you are in human form and only in certain locations where you have not yet defeated the area's Boss, but they will spawn regardless of what covenant you're in. Unlike human PvP invaders, these scripted NPC invasions can occur even if you are playing offline, so long as you are in Human form and the area Boss is still alive.
Many NPC black phantoms drop rare or unique items either when slain or at a set location elsewhere in the game once they have been slain, so they are worth locating and defeating. In a few cases, such as with Darkwraith Kirk below, the phantom will not spawn in an area where the Boss fog gate is blocked by a golden fog (certain zones are blocked by such fog and the "Great lord's power" until the player obtains the Lordvessel item). If a player enters an area that still has the boss fog blocked by golden fog, such as the Tomb of Giants or the Demon Ruins, the area is typically locked against PvP (and may also be missing bonfires) even if the player is in Human form such that neither player nor NPC phantoms will invade. Similarly, the player will not be able to see any summon signs for coop play, and the complete absence of such signs can be a good indication that the area is not open to PvP.
Locations of NPC Black Phantom Invasions (when Player is in Human form and area Boss is not yet defeated)
- Maneater Mildred in Blighttown swamp. If you defeat this Phantom you may summon Maneater Mildred to assist you in the boss fight against Quelaag later on.
- Paladin Leeroy in the Tomb of Giants. In order to ensure Leeroy invades, the player should already have the Lordvessel and the golden fog blocking the path to Gravelord Nito should be gone. This Phantom may also be summoned to help you kill Pinwheel in the Catacombs.
- Xanthous King Jeremiah in the Painted World of Ariamis.
- Darkwraith Kirk, Knight of Thorns (pictured above) in The Depths, Demon Ruins, and Lost Izalith. In order to ensure that Kirk spawns in the Demon Ruins, the player should already have the Lordvessel before entering the Demon Ruins area.
- Marvelous Chester in Oolacile Township.
Note that there are also various other instances of hostile NPCs that are hostile to the player and will attack on sight, but those NPCs do not appear as invading Black Phantoms and importantly will not trigger a warning message to the player that they are invading. These include, depending on the player's progress through the storyline and game areas, the Crestfallen Warrior in New Londo Ruins, Prince Ricard in Sen's Fortress, numerous NPCs in Darkroot Forest (some of which respawn), and certain Way of the White clerics in the Tomb of Giants. The only real difference between these NPCs and Black Phantom NPCs is that, in addition to not looking like phantoms, the non-invading NPCs can be encountered even if the player is Hollow.