Parallax

We know "“ Parallax was featured in the failed Green Lantern movie and was nothing else than a cloud (just like Galactus was, for that matter, in Fantastic Four: Rise of the Silver Surfer). But Parallax is really one of the biggest threats faced by the Green Lantern Corps, being basically the embodiment of Fear "“ even the Spectre fears it.

Essentially, it is the power beyond the yellow rings. As revealed in the comics, it was a parasite from the beginning of time and that was born from yellow part of the emotional spectrum. As such, it was sentient and able to destroy entire world with fear alone. Billions of years of imprisonment weren't enough to weaken it.

Parallax possesses so much power that he can influence even the strongest superheroes, including in here Superman and Wonder Woman. And this is a force to be reckoned with.