Who said "Your mortality is your greatest weakness."?

This quote is attributed to Green Goblin.

Your mortality is your greatest weakness. - Green Goblin

"Your mortality is your greatest weakness."

Green Goblin Death

"Out, am I?"

"You know how much you've sacrificed to fight me? Everything! But the cunning warrior survives by admitting what he is."

"The cunning warrior survives by admitting what he is."

"I'm something of a scientist myself."

"Death doesn't scare me anymore."

"Death and I are old friends."

"Welcome to my world."

"Death is just the beginning."