The Mindless Almighty

"So, isn't this terrifying? I'm terrified too... Giygas cannot think rationally any more, and he isn't even aware of what he is doing now. His own mind was destroyed by his incredible power...What an all-mighty idiot!"

- Porky Minch describing Giygas, EarthBound

A (usually) mortal being falls to the temptations of attaining significant and often god-like power and eventually succeeds; but where temptation proved too great for them, the power proves ten times more so, and they begin to literally lose their mind. Sapience, sentience, individual will, sense of self&mdash;at least one of more of these will end up buried or destroyed, possibly completely, from sheer force of intake. Alternately, someone who is already a deity (or at least strong enough to be one) undergoes a further enhancement that pushes them beyond their bounds, eroding their mind and/or soul - often until they're an empty shell of their former self. Finally, some deity-like beings... simply turn out to not be all that smart to begin with.

In summary, With Great Power Comes Great Insanity and the potential to create The Mindless Almighty.

The Mindless Almighty is a being with god-tier power or better, but at the cost of severely diminished or nonexistent capacity for cognition - bonus points if obtaining that power was exactly what turned the new deity's mind into a George Forman grill. Mindless Almighties are often effectively omnipotent vessels, driven by nothing but the most instinctual impulses - aggression, rage, simple curiosities, and hunger are some of the most common ones. This state often draws comparisons to that of a wild animal or a child... at least by human standards, anyway.

Many animals display their own form of understanding and self-awareness in ways we humans have yet to fully understand - but even the most "intelligent" animals are still incredibly dangerous if they go feral. The idea of such a ravaged mind being likened to that of a child is technically more accurate: in psychoanalytic theory, the mind of a newborn child is regarded as the purest form of id. If the deity is a literal child, that's Goo-Goo Godlike.

Becoming a Mindless Almighty may also transform the victim into an Eldritch Abomination if they weren't one already. Cosmic Horror Stories employ this trope frequently, as monsters like some of the Elder Gods can be far more frightening when they're not acting out of malice - any morality or intelligence they possess (if any at all) might be completely alien to us, and the concept of our own existence might not even occur to them.

Compare:
 * Mad God, which overlaps significantly due to the base concept of "deity whose mind is shattered".
 * Tortured Abomination, where a sufficiently strong Eldritch Abomination is subjected to enough torture that they are rendered 'feral' enough to lash out (or worse).
 * Severe cases of Superpower Meltdown or being Touched by Vorlons.
 * With Great Power Comes Great Insanity, an arguable Supertrope.

Contrast:
 * King of All Cosmos, where the deity is more highly eccentric or outright weird than anything else, though it's still possible that their mind is fried besides that.
 * Goo-Goo Godlike, when a being with god-like power is still in the actual stages of infancy and hasn't developed their intelligence to begin with.
 * A God I Am Not, for characters who are fully aware of their godlike power but still have the humility (and thus 'sanity') to refuse to think of themselves as such.

Anime and Manga

 * An Incarnation of the Radius from Sword Art Online: Ordinal Scale is a demon-goddess meant to serve as the Final Boss and main villain of the titular Fictional Video Game in the original Sword Art Online - but after Big Bad Kayaba Akihiko turned the MMO into a deathtrap, the plot no longer mattered and it went unused. Tetsuhiro Shigemura, the villain of Ordinal Scale, uncovered it while data-mining and downloaded it into the game to use against the heroes. While it clearly had the raw power worthy of a game’s main antagonist, it entirely lacked personality and seemed to be guided mostly by programmed AI patterns. (VS Battles Wiki has more on this here.) Tetsuhiro may have chosen it for this reason, as he wanted a vessel to reincarnate his deceased daughter in the virtual world.
 * Naruto:

Comic Books

 * In the Preacher comics, is revealed to be an example of this once Jesse learns more about the being.
 * Green Lantern: Larfleeze is the only Orange Lantern, and having on hand the source of his own power made him ageless and incredibly powerful. But that same source drove him into becoming Greed incarnate, wanting only riches, and only for the sake of having them, not wanting and even getting angry at the visage of other individuals.
 * This is discussed in The Sandman a few times. As Dream puts it, he and his siblings are technically not gods; they are anthropomorphic representations of abstract forces, with rules and provisos to keep them in check. That's why it's really bad if a human gains access to such power:
 * John Dee acquires Dream's Ruby and attains the power to warp people's minds, both in and out of the Dreaming. It turns him into the villain Dr. Destiny, a serial killer that has battled the Justice League.
 * Also mentioned about what happens to humans used as vessels for the supernatural: They can't handle the onslaught of power or awareness equivalent to a god, and may prefer if they didn't survive the outcome. Brute and Glob said that one of their Sandman incarnations, Wesley Dodds, lost his mind after they gave him Dream's power, so they tried seeing if a dead person could handle it better. Hector Hall does, but there's the whole problem of him being dead so his reach only extends over one boy's mind. His widow Hippolyta Hall is reduced to a raving homeless woman after.

Film

 * Averted in Bruce Almighty. Bruce is a down-on-his-luck reporter who thinks God has it in for him, so God gives him His powers, telling him, in so many words, "let's see if you can do better". Spoiler alert: Bruce cannot do better, but not for lack of any lost cognition as opposed to his pre-existing human flaws.

Literature

 * A classic example is Azathoth from the Cthulhu Mythos, literally referred to as the "Blind Idiot God". Where Nyarlathotep was actively malicious towards humanity to a degree, and Cthulhu even had aspirations to bring back the Old Gods, Azathoth is far beyond either of them in power, but comparatively is utterly lacking in motive of any kind. H. P. Lovecraft conceived it as "The Nuclear Chaos" that mindlessly drives the forces of physics and may have created our universe - and as such, it embodies this quite literally.
 * Later writers made it so that this wasn't always the case, and instead became that way upon losing its mind; August Derleth in particular portrays this as divine punishment from the Elder Gods.
 * Azathoth also reproduces by fission, as does its offspring -- it's not uncommon at all to liken ol' Azzy to the universe's most powerful amoeba.
 * In His Dark Materials, it's eventually revealed that.

Tabletop Games

 * Dungeons and Dragons:
 * Banghtu, the orcish god of strength, has almost limitless physical might, but he's known for being woefully stupid. The Monster Mythology splatbook gives him an Intelligence Score of only 3 (putting him below most mortal children, orc or otherwise). Naturally, he values strength and little else besides - he's also completely loyal to his father Gruumsh, the head of the orc pantheon.
 * Leviathan, one of the Eldritch Abominations detailed in Elder Evils, is an entity that took form from a leftover aspect of Chaos after it combined with Law during Creation. Best described as “mindless”, it is driven by little except raw instinct.
 * Juiblex is a grey area here. A powerful demon lord, it supposedly has an intellect and mindset that is alien and incomprehensible even to other demons. Some sources rate its INT at 1 or even zero, portraying it as mindless, while others give it genius-level or even godlike Intelligence, stating it even knows the true names of the most powerful obyriths, using this knowledge to manipulate the Abyss itself. Whatever the case, Juiblex seems to have the simplistic mindset of the oozes and slimes it holds dominance over - it is concerned only with devouring, consuming, and destroying everything, barely even acknowledging mortal races. In fact, certain sources claim that evil cultists who worship Juiblex actually gain their divine magic from either Tharizdun or Ghaunadaur, with some even suggesting that Juiblex is a lesser aspect of one of them. Possibly the most likely theory is that Juiblex does indeed have intelligence bordering on godlike, but only in regards to the Abyss and its history and denizens, and has no interest in anything beyond it.

Theatre

 * Some of the malevolent beings in Hatchetfield are this, which is good for the human inhabitants trying to survive in the various timelines. They can then take advantage of the childlike or wild tendencies to retaliate.
 * In Black Friday, if the Wiggly brainwashing gets to the adults, they attain both powers and a strong desire to kill for a Tickle-Me-Wiggly doll. Some, as a result, become irrational. In an ironic case of this, sociopathic Linda Munroe is recruited by Uncle Wiley to serve as the prophet for the Cult of Wiggly.
 * Blinky in "Watcher's World" wants the theme park residents to adore him, and for the Snigglys to be happy. Anyone who hates Blinky or speaks up about the unfair Sniggly conditions may find themselves near-beaten to death or hunted down like prey. That's because it depowers him..

Video Games

 * Bowser's Fury is a odd version of this that may or may not be Played for Laughs. As Fury Bowser, the king of the Koopas is so powerful that he can affect the weather, summon burning blocks from the sky, and corrupt innocent cats into his minions. He is also completely irrational, with no personality displayed beyond a constant angry glare and and a single-minded instinct to kill Mario. How did Bowser become so powerful and berserk?
 * The final boss of EarthBound is described as such by his Dragon . His attacks are preceded by completely random statements in this form, and the attacks themselves are the Trope Namer for You Cannot Grasp the True Form.
 * Final Fantasy X:.
 * Sonic the Hedgehog (2006): Justified. Iblis is a mindless monster with godlike power because.
 * The Legend of Zelda: Breath of the Wild: Calamity Ganon, which is revealed to be . Indeed, Calamity Ganon is incredibly powerful, capable of constantly resurrecting his minions, but has nothing resembling sentience or personality and usually appears a red-purple cloud of pure malevolence.
 * Xenoblade Chronicles: . Xenoblade Chronicles 2 further elaborates on that:.
 * At the climax of Xenoblade Chronicles 2, . Outside of the main storyline, the optional Blade Herald is incredibly powerful, and also can go berserk and destroy everything on her sight under certain circumstances - her last driver killed himself to make her stop before she completely destroyed the kingdom of Tantal. The party outright gets a warning about this from the Tantalese before awakening her.
 * Many of the Mega Man Battle Network series' final bosses are incredibly powerful programs or viruses packing godlike power. Some, like the Life Virus and the Cybeasts, are basically feral and uncontrollable wild animals. Then there's Alpha, an utterly alien creature that is literally the old internet itself, presented as an outright Eldritch Abomination with the intellect of an amoeba that lives solely to assimilate the Net and all its inhabitants into its being. But the unifying thread behind all of them (save for Duo, an intelligent being) is that they are irrational, mindless beings that have far too much power for their own good.

Western Animation

 * Season two of The Owl House hints that.