The vampire. A legendary creature that lives in the shadows and preys on humanity.

What is your favorite anime that is a maximum of 2 seasons long that you would recommend?

It has to be DEATH NOTE! It begins with a high school student, Yagami Light who finds a supernatural book which grants its user the ability to kill anyone whose name and face he knows.
DEATH NOTE being its obvious name.
The series centers around Light's attempts to create and rule a world free of evil as God of the “New World” using the notebook, and the efforts of a detective known as L to stop him. To add to its amusing story, the OST is also amazing and addictive.
It is recommended especially to those who like crime investigation, intrigue and thriller genres.