File:Lock.png|thumb|279px|A locked Cabinet. Note the two meters describing the number of lockpicks needed and the physical integrity of the door.
A''' lock''' is a simple or electronic machine that secures a valuable container until some kind of tool or information (in the case of an electronic lock) is used to deactivate the device. Locks appear in all 3 ''Deus Ex series|Deus Ex'' games.
In the Deus Ex|first game, locks appear both as traditional and electronic (keypads). Traditional locks have a meter indicating their "Lock Strength" and one indicating their "Door Strength". The Lock Strength must be taken to 0% of 100%, though it can start at any number in between. One lockpick will lower the percentage by a certain number, and this is determined by the Lockpicking skill. The Door Strength can be lowered through striking the door with a solid melee weapon if it is low enough, or using explosives such as the GEP Gun or a LAM. NanoKeys on the keyring can be used to instantly unlock a container with no hassle, but they must be found first and there is not a Nanokey for every container in the game. Electric Locks, or Keypads, will activate once the correct code has been entered, or a Multitool (DX)|multitool is used to activate it. The longest Keypad code is a 7-digit code in the Brooklyn Naval Shipyard, and they may be as short as 2 digits. Keycodes can be found written on paper and in datacubes, but the player can always open the keypad with nothing but the code, such as guessing or having prior knowledge of the code. There is no penalty for missing a code.
If a player is spotted by friendly AI's when he's lockpicking or bypassing they might turn hostile.
In Deus Ex: Invisible War, there are still interactive electronic and simple locks. All interactive locks can be opened through explosives, softkeys or universal Multitool (DX2)|multitools, which will now open a metal lock on a door along with keypads, which can no longer be used button-by-button as they were in Deus Ex. The Keycode must be read to access a keypad, and the code is never revealed to the player. Many more locks can now be opened through Computer skill|hacking a computer and selecting the "open" queue.
In Deus Ex: Human Revolution, only electronic locks can be found throughout the game. They can be accessed by the Hacking (DX3)|hacking minigame or by entering a four-digit code. Unlike Deus Ex, they are always four-digit and they can't contain symbols such as "*" or "#". Those symbols on the keypad are replaced with the "Close" and "Undo" buttons. If player has been given the code, it will be displayed when the right keypad is used.
If player has missed the code, no penalty will be given, however, if he has failed to hack the device it will be locked down for 30 seconds and an alarm may sound.
Dxhr 2013-02-18 15-49-23-20.jpg|An electronic lock
Dxhr 2013-02-18 15-49-45-03.jpg|GUI
Dxhr 2013-02-18 15-50-52-46.jpg|Device under lockdown
Dxhr 2013-02-18 15-52-38-67.jpg|The code displayed right next to the appropriate lock.