In Dream Lands and Spirit Worlds, there is often an Eldritch Abomination who is able to harness the limitless power that exists there. An omnipotent Reality Warper who can fully utilize the concept Your Mind Makes It Real. Sadly, the bane of many of these creatures is that this power only exists in their native world. Ergo, if they try something like invading reality hoping to use their near infinite power to Take Over the World, they'll usually find that their power didn't make the trip with them.
An extremely literal case of Reality Ensues. If the creature relies mostly on its powers and is naturally physically weak, it's Unskilled, but Strong. If the creature is still able to cause trouble even without its god-like abilities, that's Brought Down to Badass.
In the event the creature does manage to bring its omnipotent powers with it into the real world, be prepared for the End of the World as We Know It.
The creature may or may not be a Domain Holder.
- Within a dream, Yuko from The Demon Girl Next Door can conjure into being anything her imagination can come up with—unfortunately, with her being a bit of an airhead with an extremely sheltered upbringing (somewhat justified for being an Ill Girl most of her life), her imagination has trouble coming up with very much. Her Whatever Staff, already capable of defying the laws of nature in the real world, is practically a Reality Warper when she brings it into the dream world. Screw entropy, screw probability, screw thermodynamics, screw logic, if Yuko thinks it'll work, it'll work—the only catch being that doing the impossible in a dream is incredibly taxing on her very limited magical power and it quickly runs out; doing such things in reality is completely beyond her capacity. For now.
- Played for Drama on the protagonist's side in the fifth Yo Kai Watch movie. The animated yokai world is being turned into the real world by a mysterious force. The yokai find in this new reality that their powers are weaker. Jibanyan's Rapid-Fire Fisticuffs become a much more realistic speed and end up underwhelming.
- Ashley Guthrie, one of the 'slashers' in Hack/Slash, retreated into the Dream Lands when he was murdered on earth. In the dream realm, he is almost omnipotent. When forced back into the real world, he is almost powerless (and bound into the form of the teddy bear that was used to smother him).
- In The Sandman, John Dee is a shriveled, malnourished old lunatic in the waking world, but when he got his hands on the Materioptikon, enabling him to tap into The Dreaming, he became powerful enough that he not only drove a whole diner full of people insane, but he also caused a wave of homicidal madness to spread out over the world. Even Dream, who created the Materioptikon, nearly died at Dee's hands, surviving only because Dee destroyed the Materioptikon in the mistaken belief that doing so would kill Dream.
- In Max Landis' Super Mario World, humans have extraordinary strength and durability in the Mushroom World and other dimensions, giving them a huge advantage over the inhabitants. The climax of the script involves Wario being dragged to the real world, as it's the only way to inflict damage that sticks.
- In the A Nightmare on Elm Street series, this is one of Freddy Krueger's Achilles Heels. Within the dream world, he's pretty much a fear-empowered god. Outside of it, he's only a guy with a bladed glove that is somewhat harder to kill than a normal man, but die he does... until the Sequel Hook appears, that is.
- Both played straight and subverted in Last Action Hero. When both Action Hero Detective Jack Slater and Professional Killer Benedict escape the Film Within a Film and reach Danny's "real world" they both have to get used to the fact that Reality Ensues and the real world is very different from the over-the-top action movie universe they've inhabited. Jack is somewhat dismayed to learn that a lot of his tried and true techniques don't work; in real life cars don't explode when you shoot them in a random spot, and trying to punch out a glass window hurts like hell and is likely to injure you. Combined with him being stripped of his Plot Armor, this makes Jack considerably weaker in the real world than he is in the movie. Benedict, on the other hand, is delighted to learn that some of the tropes that work against the bad guy in movie world, such as Instant Emergency Response, don't happen in the real world and Apathetic Citizens in a rundown part of town don't care when you kill somebody for no reason. If anything, Benedict has the advantage over Jack in the real world, a fact which Benedict gleefully boasts about in their final confrontation.
Benedict: Here, in this world, the bad guys can win!
- The Matrix:
- This is what happens to Neo when he's disconnected from the Matrix and wakes up in the real world for the first time.
- Smith, a powerful rogue computer program, could only interact with the real world by possessing the body of someone that he had taken over in the Matrix, and he notes that real human bodies are really weak compared to the abilities he's used to possessing in the Matrix.
- And when Neo and the body possessed by Smith fight in the real world, there are no fancy martial arts, no gravity defying jumps or displays of Super Strength that both showed in the Matrix, just a pair of guys awkwardly grappling and trying to slam each other into walls or grab anything that can be used as a weapon.
- In The Wee Free Men, the Grim Hounds are instantly incapacitated when they cross over from the fairy realm to reality, because their razor teeth start cutting the insides of their own mouths.
- Thud! has the Summoning Dark, an entity of vengeance capable of crossing a million dimensions in the blink of an eye, but unable to cross a room. It possesses people to do its work, although Heroic Willpower is able to keep it trapped.
- In C. S. Lewis's The Magician's Nephew, this phenomenon keeps Jadis from conquering our world with her magic, but even here she keeps her strength sufficient to rip an iron crossbar from a Victorian lamppost. Far worse for her is the Wood Between the Worlds; there she is weaker than Digory or Polly, gasping for breath, stooped and staggering: she herself says it is literally killing her.
- In The Good Place, Michael and Janet lose their otherworldly powers when on Earth, though Janet still knows everything up to the point when she left due to the nature of her existence.
- Mega Man Battle Network 6: Net Navigators, normally cyber-entities, can manifest in the real world through the newest technology called Copybot; the Navi is uploaded into the bot, which then shifts shape into the Navi in question. The uploaded Navi is limited to their most basic of abilities while inhabiting a Copybot; its operator cannot "feed" them Battle Chips.
- This applies to most protagonists in the Persona series. In metaphysical environments like the Dark Hour, TV World or Metaverse they have access to a powerful type of Guardian Entity, but in mundane reality it takes a lot of focus and experience to manifest a persona. Most dont realize its possible at all.
- The Elder Scrolls series has the Daedric Princes, the "original spirit" divine beings who did not take part in the creation of the mortal world (known as Mundus). Unlike the Aedra, they did not sacrifice any of their power during creation and remain truly immortal. Each has a particular sphere, which they are said to govern from their planes of Oblivion which they inhabit and rule. (In some interpretations, a Prince's realm is considered an extension of that Prince themselves, as their "body". Furthering the "body" analogy is that while a Prince has absolute power in their realm, it doesn't translate into omniscience within that realm.) However, because they did not participate in the creation of Mundus, the Princes are subject to metaphysical barriers which prevent them from manifesting at full divine power in the mortal world outside of some very specific circumstances. As such, the Princes prefer to work through mortal agents to accomplish their goals within Mundus. Mehrunes Dagon is one of the few Princes who has been able to manifest at full power several times in history, causing massive destruction each time and requiring the intervention of other deities (Almalexia in the late 1st Era when he destroyed Old Mournhold and Akatosh himself to end the Oblivion Crisis).
- Whateley Universe: Spirits that are strong enough to manifest outside of Astral Space have an energy requirement to manifest, making them weaker in the real world than in the Astral.
- In one episode of Super Robot Monkey Team Hyperforce Go!, Skeleton King traps the Hyperforce in a shared dream world, wherein his power is greater than ever, effortlessly Curb-Stomping the entire team. After the Hyperforce awaken and escape, however, Chiro drags Skeleton King back to the real world with him when he awakens. Skeleton King's power is greatly weakened here, even moreso when the morning light starts burning him.
- This trope actually applies to the humans in Gravity Falls: Bill Cipher usually interacted with the world through the mindscape, which he has endless influence over, but people can fight him back by controlling their own dreams. Upon entering the real world, Bill's powers evolve to full-fledged reality warping levels, while others are no more powerful than normal. Despite his newfound ultimate power, however, he cannot leave the magical boundaries of the titular town.
- In Justice League, Doctor Destiny is omnipotent when operating in people's dreams, but he is easily taken out by Batman in the real world, who has taken three cups of coffee to avoid falling asleep.
- One episode of Teenage Mutant Ninja Turtles (2012) has the Dream Beavers, nearly invincible when inside the dream world, but reduced to cute plushies when they're forced into the real world.
- Poet Anderson: The Dream Walker: Jonas and the other lucid dreamers are regular humans at day, but powerful in the dream world, having the ability to control aspects of said dream world or create objects in order to protect innocent dreamers from the evil monster of nightmares.
- In one episode of Darkwing Duck, Darkwing and Morgana tangle with Nodoff, the king of dreams. In Dream Land, Nodoff is a nearly omnipotent Dream Weaving Trickster who can reshape the world or give himself new powers and abilities with a thought. However, when Darkwing blasts him with his own sleep sand, Nodoff is transported to the real world, where he is basically just a short gremlin with no powers.
- In Teenage Mutant Ninja Turtles: Back To The Sewers, while in the digital domain of the internet, the Cyber Shredder could do virtually anything due to be made of data, much like Viral, whose body he had taken over. Upon crossing into the real world, he lost most of these abilities due to being matter now. Nevertheless, he was still dangerous due to his naturally fighting abilities along with being able to interface with computers.