Satan, The Deceiver and Adversary
And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
Revelation 12:9 KJV
Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour
1 Peter 5:7 KJV