Hal Jordan's enemies: Parallax (Evolution)

Parallax (unlike most characters) has not changed throughout its history, and has remained evil, manipulating, and conniving. Although it has become possessive and more prone to attack Hal Jordan, out of anyone. Sinestro is currently the host of Parallax due to the events of Wrath of the First Lantern. Although it's more of the way that Sinestro is in more control of what Parallax is over him.