How to write a villain

 There are certain characteristics that recur in some of the most memorable movie villains

The mirror villain 

Opposite of the hero, but shares certain traits, values, or methods. Two sides of the same coin, for example, magneto to professor X, or Kylo Ren to Ray and Voldemort to Harry Potter, mirror villains are best utilized while being used not only for creating external conflict within the plot but internal conflict with the development of the protagonist, The Joker from the Dark KNight is an example of a mirror villain

Looming threat

Villains whose threat is constant despite their limited presence in the movie Seven by Andrew Kevin Walker. John Doe makes two brief appearances before his main reveal. He firstly poses as a photographer at a crime scene, then the two protagonists are ambushed outside his apartment. He then finally reveals himself with blood all down his shirt. To keep them a threat they have to show the aftermath of the villain's actions so we can see what they are capable of.

The villain protagonist 

They are the hero, but also the villain; for example, Patrick Bateman in American psycho. A villain protagonist should hold some promising traits to keep the audience interested.