Omnipotence

There are different definitions for Omnipotence:

• The ability to do anything non-contradictory. This definition prevents logical contradictions.
• The ability to do anything, this definition leads to logical contradictions.

The problems occur by asking questions like "Could God make a stone so heavy he can no longer lift it?" If he can't do it, then he is not omnipotent because he should be able to create such a heavy stone, if he can do it, then he is not omnipotent, because he can't lift the stone. There are many variations of the problem, for example: Could God create something stronger than himself ? As no character in the Supernatural Universe is omnipotent by either of these two definitions, no such problem has arisen on Supernatural.

Characters with this ability

Omnipotence

No entity in the Supernatural universe is truly omnipotent in the sense of the common definition of the word.

Nigh-Omnipotence

Entities that are the closest to being truly omnipotent, possesing nearly unlimited power that can create conscious beings, new realities, or at least warp them to an unlimited extent. However, by definition, each of them have weaknesses of some kind that prevent them from achieving omnipotence.

• Death - Death holds immense power which is far greater than Archangels. His power is so great that he can accomplish extremely impressive feats of power such as flooding the earth, creating an eclipse by re-aligning the solar system and killing lesser beings with a mere touch. According to himself, he would reap God at the end of time. However, despite this immensely cast power, he is not invincible (as he was killed by his own scythe) and there are still many things he can't do (such as break out of the spell the Winchesters bound him with). 
• God - God possesses near-infinite power, being able to do almost anything that he desires. It is shown that he isn't fully omnipotent, contrary to what most people believe, as he can't instantly kill his older sister, the Darkness. However, through his own power, he was able to create beings who helped him defeat her, although barely. He also is said to have no power over the Empty and, according to Metatron, had to put in a degree of effort to manifest creation and couldn't have done it with a simple snap of his fingers. Being almost omnipotent, he also has the ability to grant himself more abilities, among those were the ability to speak French and play guitar.
• The Darkness - The Darkness is the most powerful entity in existence, more powerful than God himself. The latter, her younger brother, stated that even with all four archangels fighting against her the first time, along with himself, victory was barely achieved. Even after withstanding a combined but sequential attack by powerful supernatural beings during a second confrontation, she still proved to be stronger than God when she easily stopped him from trapping her again, effortlessly overpowered Lucifer at the same time, and fatally wounded her brother, all before regenerating fully and walking away. Not long after, upon reconciling with God, Amara was able to heal the fatal damage her nigh-omnipotent powers did to him, even when he was very close to death, without any difficulty.
• The Shadow (within the Empty) - The Shadow is the supreme ruler of the Empty, a place of nothingness inhabited by every deceased angels and demons where they slumber for all eternity. The Entity has unrivaled control over it, even Heaven, Hell and God does not have authority on the Empty. Like the inhabitants of the Empty, the Entity itself sleeps for eternity and unlike them, it needs to sleep. If any being is awakened in the Empty, it affects the Entity and awakens it from the eternal sleep which causes it pain. It was also powerful enough to easily break open Heaven's gates, even the ones closed by Metatron's irreversible spell and effortlessly defeat all the remaining angels. Despite all this power and complete authority over the Empty, the Entity cannot force a being to sleep and the Entity must either convince them to return to sleep in their own or expel them.

Mid-Tier Nigh-Omnipotence

Entities stronger than the lower tier but still noticeably weaker than the higher tier.

• Jack - As the Nephilim child of Lucifer, the second born archangel, Jack possesses unimaginable power. He was able to open a gate to an almost inaccessible section of Hell and nearly released the Shedim, telepathically awakened an angel sleeping in the Empty unintentionally, which was impossible according to The Shadow, and rid the entire world of their ability to lie by commanding it. Jack's power, as it continued to grow, even worried his grandfather, God, who saw him as a threat and ultimately even ditched his caring facade to make sure he won't survive. Billie confirmed that if Jack unlocks his full potential, he will be able to kill God.
• Lucifer (after consuming Jack's Grace) - As the second-born archangel Lucifer was already extremely powerful, and after consuming most of his son's grace, the Apocalypse World Michael described him of being powerful enough to destroy and remake the universe if he put his mind to it, which Lucifer claimed he could do in just a matter of days. However Dean, while using the full powers of the Alternate Michael was very challenging for him, and only lost partially due to Lucifer having much greater fighting skills.

Lower Tier Nigh-Omnipotence

Entities of nearly unlimited power, however there are still many thing they aren't capable of.

• Archangels - Archangels have a tremendously vast supply of power, they can accomplish incredible feats of power such as obliterating and banishing common Angels with gestures, finger snaps, winks or even simple thoughts. However, there is still much that they can't do: find humans who are protected by enochian sigils, forced possession of a vessel, or breaking out of Lucifer's cage.
• Castiel (temporarily; while empowered by Purgatory's souls) - Castiel's powers were exponentially magnified as a result of having absorbed all the souls from Purgatory. At this level of power, Castiel could annihilate Raphael, the third oldest Archangel, with a snap of his fingers, destroy thousands of angels In Heaven and (supposedly) erase Hell from existence. However, despite his newfound power, he was still keen on keeping Michael and Lucifer locked in the Cage (although he didn't seem too concerned about the possibility they might get out) and Death calmly stated he was no god and was confident he could kill him, meaning Castiel's powers were still not on the level of God or Death.
• Deities (formerly) -  While they were still massively worshiped, they possessed a tremendous amount of near-unlimited powers and were next to invincible. However, as the pagans have lost most of their followers the deities' overall power is tremendously reduced.
• Metatron (temporarily; while connected to the Angel Tablet) - Empowered by the Word of God, his angelic powers were greatly enhanced and common angelic weaknesses such as holy fire proved to be ineffective against him.

Extremely powerful

Entities of immense power, that can apparently warp reality or destroy and create things to a limited extent.

• Deities - Despite only being a fraction of what they once were. Many of the deities are still much stronger than regular angels and demons. Some have even prove to been able to influence archangels, albeit to a very limited degree.
• Jesse Turner - Jesse's powers were activated and strengthened by Lucifer's presence on earth and during that time has accomplished incredible feats of power such as exorcising a demon by verbally telling them to leave their host, turning an Angel into a figurine, conjure beings into existence simply by believing in them, etc. According to Castiel, at the peak of his power, Jesse would have been able to destroy the entire host of Heaven with a single word, though this has not been proven. After Lucifer's death, it is unknown if he is permanently powerless.

See also

• Omnipresence
• Omniscience
• Reality Warping