Parallax

Here is yet another of the Lantern supervillains who have posed a threat to the entire universe. Basically, Parallax is actually a parasite, existent from the dawn of time and being the embodiment of fear itself. As such, the first one he possessed was the strongest human Lantern of them all, Hal Jordan.

Later on, it was revealed that the parasite has been locked inside the Central Power Battery on Oa and named by the Guardians as being just an impurity. Under the control of Parallax, Hal Jordan easily defeated the task force sent after him (which included superheroes such as Wonder Woman and Martian Manhunter) and sent them back to Earth.

Only Spectre's intervention freed Hal from Parallax "“ when the mightiest of all DC superheroes comes to aid, it is pretty clear that Parallax is one of the biggest supervillains of the DC comic book universe.

Among the superpowers of Parallax, besides the usual ones, we can also mention reality and time manipulation. One of his greatest feats of strength is that he can instill fear even in superheroes such as Superman (though he didn't manage to do that with Batman and Kyle Rayner).