Satan, the devil of Christian, Islamic and Hebrew belief, comes from the Hebrew word ha-satan (the accuser). He was God’s spy, a member of the divine court tasked with gathering information.
He did not make evil himself, but rather illuminated and provoked evil in mankind:
And the LORD said unto Satan, Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil? and still he holdeth fast his integrity, although thou movedst me against him, to destroy him without cause.
And Satan answered the LORD, and said, Skin for skin, yea, all that a man hath will he give for his life. But put forth thine hand now, and touch his bone and his flesh, and he will curse thee to thy face.