"As harmless as they might appear, Parasites are the evil scum of the earth... and they all deserve to die."
— The Queen of Maggots, Chapter 1.
The parasites are the main antagonists of the game and the main goal of Susan Ashworth is to kill them before they hurt her or anyone else. There are 5 parasites in total.
The parasites' appearance differ greatly from each other.
Parasites are shown to be very deranged and ruthless creatures. Some parasites are shown to be very deceiving making it difficult to tell one from an ordinary human, as they pretend to care about Susan- and others- when in reality, they only wish to cause them extreme pain.
In order of appearance.
|Xavier Zelmann||Known more as Doctor X, who seems to be a calm, kind doctor/psychiatrist of the Cedar Lake Hospital. However, he shows his true intentions at the end of Chapter 2.|
|Pest Control Man||A man in a jump suit who appears to have some sign of facial hair. He is called to deal with the cats. However, he kidnaps Susan and tries to kill and eat her for dinner. He left behind a loaded revolver hoping Susan will kill herself after Gladys destroys Susan's face with bleach. His real name is never disclosed.|
|Gladys||Known more as the Pest Control Man's Wife, she appears to have a zombie-like appearance as well as wearing a bloody nurses' costume. She orders her husband what to do and is always afraid of losing him. Unlike her husband, her real name is mentioned in the credits. Her actions are revealed during Chapter 4 and she will also kill Susan if caught by her.|
|Carpenter||A mute man that appears at Susan's doorstep with flowers, is usually assumed to be her 'Admirer'. His real name is never disclosed and his nickname is only mentioned by the creator on tumblr.|
|Adam||Also known as The Eye of Adam, which he uses as his screen name on the forum where he 'trolls' by asking people if they have a reason for dying and telling them how to do it. He is actually a crippled man who appears to be an early adult.|
- The Female parasite has character portrayal similar to that of Nurse Edna from Maniac Mansion.
- The Pest Control Man is the favorite parasite of R.Michalski, due to David Firth being his favorite animator.
- In the game Downfall, the Queen of Maggots says that Joe Davis is the "sixth parasite".