What is Human worst enemy

I am not sure what is humans worst enemy. i know mine though: Pain

If your are talking about intrapersonal, i think fear and hate is humans worst enemy. Like wise one's self is also an enemy if not controlled and if no discipline is present.I guess worst enemy is still human beings, because they are dynamic and cando what ever they want. They are capable of thinking and do tactics to hurt a human or worst is to kill. Do you agree?

Definitely GREED! Which is one of the worst deadly sins man could have. Because of greed we have wars especially over oil, because other people have something we don't it causes man to steal or to destroy. Man wants EVERYTHING and money is the main problem. I know money makes the world go round but it's people quest for money that makes them greedy, greed causes so much misery in this world.

i think a human's worst enemies is theirselfs and it is everything in them, not just fears. yes you are right most of our negetive things in our personalitty comes out of our fears. but i still stick to the sentence: human worst enemy is himself:)

I feel it EGO. ego kills! its the worst thing to have on earth. its becoz of ego, human fight, they show anger and suffer from superirity complex! ego when is erradicated, ther would be big or small..ever1 would be equal and every1 would be respected...the world would be a better place to live without ego...!