Call of Duty: Finest HourEdit
In the British second level, Depot Saboteurs, a small house can be accessed, looking similar to a church. Throw two sticky grenades at it, then press the Action button. Nothing will appear. Throw one more sticky grenade and when the explosion has cleared you will see a stairway. Go down it to find a strange room.
In the room, there is the ghost of an Arab playing an instrument. He does not acknowledge the player, and keeps on playing. A Bren LMG can be found, as well as a first aid kit and more sticky grenades. On the walls there are pictures including some of SAS or PPA soldiers wearing turbans in a Jeep. The room has a mysterious lighting and a ghostly atmosphere. No one else will follow the player down there.
Call of Duty 4: Modern Warfare Edit
Appearing in Call of Duty 4: Modern Warfare, these are usually the cries of children that appear only in places of great destruction. In the level "Aftermath", when Sgt. Paul Jackson exits the downed helicopter, there is a playground to his upper left. If he were to walk over there he would find that the cries of children can be heard. In the level "All Ghillied Up", Lt. Price should be able to hear the same cries of children like before.
Call of Duty: World at War Edit
In Call of Duty: World at War, there are ghosts in the levels Der Riese, Shi No Numa and Verrückt. In Verrückt, disembodied cries and screams can be heard. In one room, there is a man screaming in agony, and in another room, a baby and a woman are crying. Also, if the chair in the left starting room is turned on (by holding X on Xbox 360, Square on Playstation 3 or F on PC) the sound of a drill and a man screaming can be heard afterwards. The ghosts cannot be seen, but heard. In Shi No Numa throughout the map some eerie whispering is heard. Also in Der Riese occasionally, standing near the power generator near the window children can be heard singing, and a woman can be heard crying near the furnace next to the Thompson.The same can be heard in the Fishing Hut in Shi No Numa.
That's not all, however, for there are multiple disembodied voices in many of the multiplayer maps as well (Hangar, Dome, and Asylum, to name a few). Not only that, but in the singleplayer mission "Semper Fi", after the marine is executed by the booby trap and the first banzai charge occurs, if the player stands by the shrine beside the trap, the player can hear a voice speaking to them. This is best heard when the volume for the music is turned down entirely.
Call of Duty: Modern Warfare 2Edit
In Call of Duty: Modern Warfare 2, in the multiplayer map Favela, if the player stands still long enough they can hear things in the background such as car horns beeping, a child saying "Daddy", a dog barking, a baby cooing, glass shattering, a door shutting hard, etc. even if the player is the only one in the lobby. These noises were likely included in the map for background ambience.
Call of Duty: Black OpsEdit
In Call of Duty: Black Ops, the only levels that seems to have ghosts in Zombies are the levels Kino der Toten and Shangri-La. Heading towards the Alley in Kino der Toten and looking at the window that is on the left of the box spawn, the player will see a door with a larger hole in it. Staying around the window a strange noise that sounds like whispering start to play.
After the players have teleported into the Pack-a-Punch room and then that gets teleported to a random room or if the player no-clips out of the map and into one of these rooms then the following can be heard. In Samantha's room (the room that's not destroyed) the player can hear her name being called and a strange child's voice (Most likely Sam's voice) can be heard at times as well. If the player teleports to the Dentist surgery, they can hear a drilling sound and a man screaming out. Due to the very small time amount you are in the random rooms it is often you will not hear some of these sounds. When a Hellhound round begins, after the Demonic Announcer says "Fetch me their souls!", if no hounds have spawned yet, one can hear a quiet, and eerie whispering. If the player goes into the dressing room and head to the window that is past the MP5K and if the player stands next to if for a while, one will hear a knocking sound being made.
In the multiplayer map Villa, one can hear the sounds of men screaming.
Call of Duty: Modern Warfare 3Edit
In Call of Duty: Modern Warfare 3, in map Sanctuary, player can hear a ghostly voices saying "Hehe, look at me, daddy! Hehe!", "Don't get too close to the road, sweetie", "Hehehehehe.", and "Sarah, don't go too far!" The voices are sound clips taken from Davis Family Vacation.
Call of Duty: Black Ops IIEdit
In the Call of Duty: Black Ops II Zombies level Buried, ghosts appear as a special enemy the player encounters when they enter the house. The Ghost is a floating woman with brunette hair and pale white skin. They are dressed in typical "wild west" garb; a dark blue blouse-like dress and black dress shoes. If they get close enough, the player may notice that they have tears streaming down from their left eye. They have purple blood and they fade away upon death.
In Mob of the Dead, rattling chains and other sounds can be heard around the prison.