Location:
Top Right Garden section
How To Summon:
Walk near the Tombstone and he will appear
How To Exorcise:
Let him follow you to the Top Left Garden section, and sit down at the table

Note: He is also used to exorcise the Jester

Location:
Inside House
How To Summon:
After a while and opening interior doors a couple of times, whilst in the house "Fear" will start to pop up in text. If you open a door and go through after a short delay he will appear in the doorway.
How To Exorcise:
When the "Fear" begins to appear, open a door and then leave the area but without using the door (such as just walking right to a different screen). Repeat this a few times and he will be exorcised.

Location:
Attic
How To Summon:
Open up the musical jack-in-the-box, and he will appear in the room.
How To Exorcise:
Take the musical jack-in-the-box and give it to the Zombie, this will exorcise The Jester.
Required Item:
Musical jack-in-the-box, from the Attic.

Location:
Upstairs Middle Library
How To Summon:
Near the middle of the library you will have a prompt to interact with a book, this will spawn Marquis.
How To Exorcise:
Walk up to him, and choose the interaction to draw a Salt Circle using the Jar Of Salt.
Required Item:
Jar Of Salt, from Bottom Right Kitchen.

Location:
Outside Left Cornfield
How To Summon:
When walking near the right edge of this screen, it will enable his interactions.
How To Exorcise:
You need to squash 4 pumpkins down the toilet in the Bottom Left Bathroom.
Required Item:
4 x Pumpkin. From Top Left Garden, Top Right Garden, Right Vegetable Patch, and Outside Left Cornfield.

Location:
Inside The House
How To Summon:
After finishing half of the ghosts, if you wait a while he will eventually appear at the edge of rooms.
How To Exorcise:
Go to the Upstairs Right Room, and summon Vortex. Wait for Killer to also be in the room on the left. Walk up to Vortex and choose the Guard interaction, this will exorcise the Killer.

Location:
Middle Floor Left Room
How To Summon:
Walk past the mirror, and after a delay you will be able to interact with her.
How To Exorcise:
Using the Red Pen, interact and choose the "Draw Ladder" option.
Required Item:
Red Pen from Middle Floor Left Bedroom

Location:
Middle Floor Left Bedroom
How To Summon:
Always available next to the Bed.
How To Exorcise:
Next to the bed interact and choose "Hang The Amulet".
Required Item:
Amulet from Middle Floor Right Room.

Location:
Right Vegetable Patch
How To Summon:
Pickup the vase of flowers and he will appear.
How To Exorcise:
Walk up to him and choose the "Touch" option.
Required Item:
Vase of Flowers from Right Vegetable Patch, just to summon.

Location:
Basement
How To Summon:
Always available in the Basement.
How To Exorcise:
Walk past the record player, and choose the "Hum A Tune" interaction with him.

Location:
Upstairs Left Room
How To Summon:
Turn the TV on, leave the room, and after you see her appear from the TV just wait a while and she will crawl in the room.
How To Exorcise:
You do not need to summon her, instead just choose the "Stab" interaction on the TV after picking up the scissors.
Required Item:
Scissors from Top Right Garden.

Location:
Upstairs Right Room
How To Summon:
Stop the kitty clock on the left of the room, and this spawns Vortex on the right.
How To Exorcise:
Take the antique box and place it on the swings just outside the front of the house.
Required Item:
Antique Box, from Upstairs Right Room.