The character's powers or artificial life support systems/spells come with a finite Power Source or number of usages. Once that fuel meter runs out, either they can never use that power again, or they die.
Usually said doom is averted before it ever comes to that, but not always- a character may have to employ Heroic Willpower to push through, learn to function when Brought Down to Normal, or use their last bit of power to enact a Dying Moment of Awesome.
Compare Hour of Power, which is limited in period but can always be reused or recharged, and Cast from Lifespan which uses a character's lifespan instead of some other sustaining power source (the two overlap in cases where lifespan is directly linked to their expression of this trope- say, a Power Armor Spacesuit with limited battery life, or a Pure Magic Being that can't easily regain mana). Compare also Power Degeneration, which often overlaps when Toxic Phlebotinum-type side effects set in or a character gets weaker as their batteries deplete. See also Justified Extra Lives, which may employ this trope as part of its explanation.
- Miroku from InuYasha. The "wind tunnel" in his hand is almost story-breakingly powerful (it's basically a personal black hole) but it will eventually consume him regardless (unless the demon who put it there is killed), but using it to inhale monsters accelerates the process, and injuries to that hand shave off even more time.
- In Maburaho, all magic users can only use their powers a limited number of times. If they use up all their spells, they die and their bodies crumble to ash.
- In The Girl Who Leapt Through Time, the main character discovers a device that allows time travel. Unbeknownst to her there was a limited number of uses, and she used them up on trivial and inconsequential things, leaving her out of uses when she really needed it to save a life. Thankfully a Deus ex Machina arrives with The Reveal.
- .hack's data drain powers increase your viral corruption, although it is possible to lower it, overuse results in random chance of various effects (both positive and negative), eventually resulting in game over from viral takeover.
- In Puella Magi Madoka Magica, in the new universe created by Madoka in the final episode, magical girl power generally works like this. Instead of becoming a witch due to having your gem corrupted, when you run out of magical power, you simply fade away.
- All superheroes in Gamma are powered by the Lambda energy in their bodies. Once it runs dry, they lose whatever powers they had.
- Spawn from Spawn had a necroplasm meter for some of his special powers.
- Hourman had exactly one hour of total time he could use to visit his father in an otherworldly realm.
- Nico Minoru's Staff of One in the Marvel series Runaways. The staff can cast any spell imaginable, but can't cast the same spell using the same incantation more than once.
- This is what makes Calvin's superpowers from the Calvin and Hobbes: The Series episode Super Calvin a Deadly Upgrade. They are fueled from his energy, and the process of getting them deactivated a gene that allows him to regain that energy. Use of his powers drains his reserves very quickly, and once it's gone, he can't get it back.
- In the Ghost Rider film, the previous Rider fades away after one last change.
- Power Rangers has invoked this twice with the Mighty Morphin Green Ranger, then again with the Lightspeed Rescue Titanium Ranger. In both cases, the Rangers originally had unlimited use of their power before the bad guys came and put a cap on it (and the Titanium Ranger was eventually able to remove his restriction).
- In Kamen Rider Den-O, Zeronos must use up a Zeronos Card to transform, and he has a very limited number of them. At one point, he actually does run out and is unable to assist Den-O with the Monster of the Week. Later, he receives red Zeronos Cards, which are still finite and offer more power at the cost of memories from his past.
- Steven Spielberg's Taken did this with a young alien boy who eventually burned himself out using his powers.
- One of the Xanth books features as a key character a little girl who appears to have the talent to have all the talents, ever. Eventually the heroes notice a pattern, or specifically, a lack thereof; it turns out that the limitation (which every talent has) is that she can only use each talent once. After this, she gets much more conservative with it; before, she was kind of a spoiled brat because if things didn't go the way she wanted, she'd just magic them into something more to her liking, and not even her parents could do anything about it.
- To clarify, she has every magic talent possible; but she can use similar talents for the same effect. For example, she could make clean drinking water by cleansing it, distilling it, reversing time to when it was clean, transmuting it, etc. In another book, The Dastard, she finds out that the limitation is actually that each spell is on a years-long cooldown. Unfortunately, his talent allows him the ability of reversing a short period of time; and he caused her not to come to the realization. So far, she still doesn't know.
- In Worm, capes whose powers come from Eden/The Thinker's dead shards have a limited well of power to tap on, and some of such characters run out during the final battle.
- Breath of Fire: Dragon Quarter has exactly this; the main character's draconic powers are limited by how long he can remain in his Super Mode state. When the meter is full, he dies. Game Over. No way to lower it, whatsoever. The game is designed with the expectation that you'll eventually overtax it and die — then you can start over from the beginning, keeping much of your character advancement and items and unlocking new cutscenes that reveal more of the story. Repeat until you can clear the game without going over.
- All of your defenses in the original Five Nights at Freddy's drain your power (and it drains slowly even if you don't use anything because of the light and fan in your room). Once it's gone, your room will go dark and you'll probably be killed by Freddy unless the clock ticks over to 6 AM.
- This also applies to your flashlight in Five Nights at Freddy's 2. Use it too much and you won't be able to look down the hall to see what's coming after you- and you have no way to defend yourself against Foxy, who can only be deterred by flashing your light at him.
- The Lightning in MediEvil can't be recharged in either game and is the only weapon with no way to restock. This was rectified in the PSP Updated Re-release the first game- now the Lightning is just prohibitively expensive to recharge.
- Emiya Shirou in Fate/stay night's Heaven's Feel scenario. He can use his projection magic only 3 times after defeating Dark Berserker with Archer's arm.
- A meta example from Metal Slug: Grenades deal a lot more damage than any of your other weapons, but you only start with 10. So it's a common strategy against bosses to use up all your grenades and apply More Dakka without trying to dodge, as getting killed replenishes your grenades and ends the bossfight faster.
- Warcraft III: In the first game, some unit abilities like the Mortar Team's Flare and the Huntress' Sentry were limited to one per unit, the expansion made it reusable after a long cooldown.
- StarCraft's Spider Mines were limited to 3 per Vulture bike, StarCraft II: Wings of Liberty's campaign has an upgrade that lets you buy more when the stock is used up.
- Puella Magi Madoka Magica fangame Grief Syndrome uses this for its Soul Limit feature. Each character has a Soul Limit stat that slowly drains over the course of the game, though some of your Soul Limit can be burned to regenerate health and even bring yourself back from the dead. Once it reaches zero, that character is Deader Than Dead and unavailable for the rest of the game.