Who are the New Testament villains?

Those religious leaders of the day who killed their own Messiah.

Judas.

Simon - in the book of Acts he wanted to buy the power of God for money. From this comes the more modern term 'Simony'.

Satan - although not that frequently mentioned he is very busy 'Behind the Scenes.'

The Antichrist, The Beast, The Woman on the horse and other figures in the book of Revelation.