Many of what are considered “evil spirits” within Middle Eastern & Asian culture – and especially in Hinduism – are known as such because Christianity adapted their gods/goddesses as foes to their true God. This is a common thread throughout history – one culture adopts another’s deities as adversaries of their gods/goddesses. In this regard, “evil” is relative. That’s not to say that many of these supernatural beings don’t have destructive sides – but whether it is fair to classify them as “demons” is debatable.
Note: Hindu deities like Kali and Bhairava (for instance) are included because they were listed in a historical compilation of demons by Collin De Plancy. I tried to be fair and include descriptions from the Puranas to balance what de Plancy said, but I can’t change the fact that he included them in his list. If you’re still offended, you can read my response to angry emails I’ve received concerning this. Learn more about my philosophy behind the classifications.