Some top secret information would be dangerous if it fell into the wrong hands. In order to make sure that this doesn't happen, the system designers make it so that if even one wrong password attempt is tried, then the person will be locked out forever, or worse, a Self-Destruct Mechanism will trigger destroying the encrypted data.
In reality, this system is fraught with problems. For one, the people who know the password could accidentally hit the wrong key (and they're bound to if they have to type in the password on a regular basis), meaning that eventually they will lock themselves out on accident. Also if any of their enemies want the data to be inaccessible, all they have to do is get access to the machine and purposely type in the wrong password to disable or destroy the data. As indicated by the Real Life examples below, actual implementations of this type of security allow a limited number of failed attempts in order to prevent accidental lock-out.
Often paired with Highly Visible Password to play up the drama of whether or not the heroes typed in the one and only correct password, and to allow the heroes to be extra sure that they didn't mistype the password.
Contrast with Password Slot Machine.
- In Majin Tantei Nougami Neuro, there is only one chance to give the password needed to gain control of HAL, an AI brainwashing people to cause destruction and give him access to other supercomputers.
- In Eagle Eye, Agent Perez tries to get into a federal employee's laptop. She enters an incorrect password, prompting the machine to shut down, and federal agents show up at her location moments later.
- In The Fly II, Bartok Industries scientists attempt to activate Martin's telepods when he escapes. This is actually a case of Two Password Attempts Ever, because when they give the wrong password at the computer's prompt of WHAT'S THE MAGIC WORD?, it gives them another chance, telling them, WARNING: INCORRECT RESPONSE WILL ACTIVATE TAPEWORM. Bartok understands that only Martin knows or would know the "magic word."
- The Da Vinci Code has this when Sophie and Langdon try to access a special ATM. The machine tells them to be extra careful because not only will it eat their card if they get the password wrong after one attempt, but the entire machine will shut down.
- Star Wars Legends: Jedi Apprentice: Lampshaded when Qui-Gon tries to guess his evil ex-apprentice Xanatos' password and muses that someone as arrogant and untrusting as Xanatos would have the computer set to trigger an alarm if even one incorrect attempt were entered. Fortunately for Qui-Gon, Xanatos' password is laughably guessable.
- In the Babylon 5 episode "Secrets of the Soul", Dr. Franklin assures the Hyachs that the medical information that they have provided is secure because it is triple-encrypted and even one wrong password attempt would destroy the data altogether. One has to wonder what he'd do if he himself mistyped any of those three passwords and accidentally destroyed the data.
- The first episode of Criminal Minds featured a computer security system called "Deadbolt Defense" which would destroy the data on a laptop after five incorrect password attempts. It's activated after the local cop enters a password on a sticky note on the laptop, so that might have been an activation code for Deadbolt Defense, rather than just a mistyped password in general. Amusingly enough, Garcia's introduction is telling Morgan that there's absolutely nothing she can do to help, he'll have to profile the password. Yet, for someone with this type of security and something important to hide (a video feed of a kidnapped woman), the actual password is apparently "entersandman," his favorite song, no capitals, numbers, or special characters. Apparently he thought Deadbolt Defense was enough?
- Doctor Who: In "42", the Doctor and Martha end up on a ship under lockdown operating on a system like this. To unlock each door they have to answer a seemingly simple trivia question someone on the ship would know, or else it stays locked and they can't retry. Unfortunately, thanks to crew rotations the people who set the original questions aren't on board anymore, the ship is in the process of falling into a sun, and Martha isn't exactly a trivia expert...
- iZombie episode "Twenty Sided, Die" has Liv and Clive discover and try to access a computer setup. Upon entering an improper password the whole system went haywire.
- Person of Interest. A more realistic version occurs in "Dead Reckoning". Not knowing how to defuse a bomb, Finch instead tries to hack the mobile phone being used as a detonator. He has five possible combinations for the unlock code, but the phone will lock him out after the first three.
- The SCP Foundation report SCP-093 ("Red Sea Object"). In the "Violet" test the Foundation team tries to log into a computer they find. The first attempt fails, after which the screen prints a message that the maximum number of attempts has been exceeded and the PC turns itself off.
- GURPS supplement Warehouse 23. Anyone trying to log on to the Warehouse's computer remotely must input two separate passwords. If the second password is incorrect the computer assumes that an intrusion is taking place and doesn't give the intruder another chance.
- Shadowrun supplement The Neo-Anarchist's Guide to North America. In certain high security areas, cardreader security access devices are programmed to signal an alarm the first time they receive an invalid code.
- In Dynamite Headdy, after the credits have rolled, a screen appears where you could enter a 4-digit password on a keypad. You only get one shot at entering the password (which changes for every playthrough). Completing the basketball minigames reveals the password number by number.
- In The Hitchhiker's Guide to the Galaxy, entering the wrong password to open the case containing the atomic vector plotter on the Vogon ship will make the case explode, killing you.
- Life Is Strange manages to subvert the trope. While most cases where you need a password or electronic PIN have a limit on the amount of guesses (as you'd expect), you can simply reverse time and try as many times as you like.
- In the Nintendo Wars series, Advance Wars: Days of Ruin (Advance Wars: Dark Conflict in Europe/Australia), The Heroes come across an underground bunker that has supplies they desperately need. The problem is, the bunker cannot be breached and they can only try the password twice. First, Brenner/O'Brian tries his military access code. When that is rejected, the team is left with one guess for a ten-digit password. Luckily Will/Ed had been talking to Isabella/Catleia an she had been muttering a ten-digit number over and over. With no other option, they enter the code. When the doors open, the team is left baffled at how she could've possibly know that code.
- In Shin Megami Tensei: Devil Survivor, Atsuro's friend 10-Bit has important information on his COMP, but dies before he can tell him the password. The COMP is set to lock up if the wrong password is entered, and the only thing you know is it's a four-digit number. The password turns out to be based on 10-Bit's name, being the maximum value of a ten-bit unsigned binary number, 1023.
- Si N sometimes has things that activate on an incorrect password entry, but most of them allow retries or resetting the trap. The only one that allows one attempt is trying to disarm the nuke (on hard difficulty) where failure releases toxic gas.
- In the Thunderbirds Are Go episode "Space Race", the Thunderbirds are attempting to deactivate a space-based automated weapon left over from an old war. It was built with a deactivation code, but they get only one attempt to use it, because any error will cause the weapon to assume the worst and destroy itself, the person entering the code, and anything else that happens to be within range.
- At Alcatraz, the locks on some of the doors prisoners were never supposed to go near were designed so that using an incorrect key would disable them. During one infamous escape attempt, one escapee had a ring full of keys that didn't include the correct one. He didn't get out that way.
- Downplayed with ATM cards. You usually get three attempts to enter your PIN correctly; the third time that you enter the wrong one will disable or capture your card and you'll then have to call your bank to obtain a new card.
- Some operating systems, mostly on smartphones, have an optional feature that will erase all data on the device after X number of failed login attempts, in case the device has been stolen.
- SIM cards on mobile phones allow 3 attempts to enter the PIN code correctly. After the 3rd failure, it can only be unlocked with the much longer PUK code.
- Certain login systems downplay this. Rather than lock the person out, each incorrect login adds a delay when checking the password, with each attempt making the delay longer. This is to discourage brute force attacks.
- In nuclear weapon storage facilities of the US Armed Forces, this trope is in full effect. Entering the wrong code to any door or access keypad more than three times not only locks you out of the system, but alarms go off that send heavily armed, highly suspicious security teams to your location. You will be detained until things are sorted out, and you will be shot immediately if you display any resistance at all to being taken into custody.