Rakshasa

Rakshasa
Powers and Abilities	Shapeshifters that can make themselves invisible.
Vulnerabilities	A knife of pure brass. Cannot enter a home without an invitation.
Appearance	Humanoid; can appear in any form it wants.
Episode(s)	2.02 Everybody Loves a Clown

Rakshasa A demon or unrighteous spirit in Hinduism that feeds on human flesh. They are shapechangers and magicians, and often appear in the forms of humans, dogs, and large birds. They can make themselves invisible and can not enter a home without being invited. According to the Ramayana, an ancient Sanskrit epic, they were created from Brahma's, the Hindu God of Creation, foot. Many Rakshasa were particularly wicked humans in previous incarnations and are known to disturb sacrifices, desecrate graves and possess human beings. Translated to English, Rakshasa means injurer. – Pad of Definitions (2.02 Everybody Loves a Clown), Official Website

In 2.02 Everybody Loves a Clown, the Rakshasa is disguised as the blind knife thrower who works with the circus. It appears to children as a clown, and, when they invite it into their home, it kills their parents. Ellen tells them the creature can be killed with a knife of pure brass. As it pursues them, it becomes invisible, but Sam manages to kill the Rakshasa with a brass pipe from the organ in the funhouse.