~ Jafar while becoming a Genie.
For I am transformed! I have left the mortal plane behind me! In truth I have risen above the mantle of godhood! Even celestial status is now below me! The Infinity Gems have given me the power of Supreme Being!
~ Thanos after being empowered by the Infinity Gems.

Villains capable of doing anything and everything to total extent or at least an extent that surpasses the human race's conception of universal laws (e.g. Yukari Yakumo has total control over limits) with very little to no limit (for instance, Anthony Fremont can do anything he wants but cannot reverse what he has done). There are some, like Kefka, who can obtain absolute power in the course of the story. These villains are not completely invincible, however, and while overpowering them is absolutely out of the question, they can be outsmarted or played in some way or another. It is also known that nigh to normal Omnipotence are reality manipulating powers, and both can also give the user a complete or almost complete collection of powers.

Nigh Omnipotence is a balanced version of Omnipotence and it can be bestowed through some other means like powerful items (like the Infinity Gauntlet created by Marvel) or some other causes like being granted Semi Omnipotence from a Deity. Despite having missing element(s) which causes the ability to be limited, the power at best is still capable of holding unimaginable power that a person could ever comprehend.

As for Omnipotence, this is when the tables start to turn. Unlike Nigh Omnipotence, this one is not gainable/giftable in any ways possible since it is only used by a Monotheistic Deity. However, the user is able to commit feats that Nigh Omnipotence wouldn't may be capable of doing, such as interfering with free will, manipulating primordial to universal forces at will and can create sentient life, among others.

Please note that these villains must be EXPLICITLY labeled as all-powerful in the story in which they appear, through their words or through the feats of magic/reality-warping that they perform.