Sentry bot (Fallout 3)

Sentry bots are a model of robot found in the Capital Wasteland after 2277.

Characteristics
All sentry bots encountered in the game have either a minigun or Gatling laser on the right pylon and a missile launcher on the left one. As expected, they are the most resilient robot in the game, with as many hit points as a deathclaw and far greater  damage resistance to boot. Furthermore, they cannot be crippled with a dart gun nor do they have any critical weak spots: Their head and legs take -50% and -25% damage respectively from all normal attacks. Its one flaw is the combat inhibitor mounted on the back and its slow turn rate, allowing the player to circle-strafe and destroy the inhibitor, causing it to frenzy (though it's pointless in areas without additional enemies). pulse grenades are very effective weapons against the bot. Using the Robotic Expert is also a good way to permanently shut it down (the talk option is useless).

Sentry bots sit at the top of the game's robotic food chain and are routinely found roaming the Capital Wasteland, either alone or in groups of two to three. The Outcasts and the Enclave use them on a regular basis, with a pair of unique sentry bots found at Raven Rock, guarding the entrance to the President's chambers. They will kill the Enclave soldiers standing at their post, allowing the player to reach Eden.

One sentry bot is posted alongside Paladin Bael at the entrance to the Citadel. It respawns, providing an endless supply of loot, but will be removed from the game after completing Take It Back!. A quest-related sentry bot is found in Big Town and can be repaired to aid the town in defending against super mutants following Big Trouble in Big Town. Another two can spawn alongside the Mechanist at Canterbury Commons.

Sentry bot
Sentry bots come in many different guises, distinguishable by their paint, which shows their affiliation (Enclave, Brotherhood Outcasts, United States Armed Forces, etc.).

Enclave sentry bot
Slightly darker in appearance when compared to the normal variant, the Enclave model boasts improved systems.

Strike Team sentry bot
The most expensive option for recruitment in Operation Anchorage is a winterized sentry bot, with a built-in minigun and missile launcher, costing 4 recruitment markers.

U.S. Army sentry bot
U.S. Army sentry bots can be found wandering about the wastes in seemingly random locations, even miles away from the nearest military installation. They can easily be recognized by their green paint job and U.S. Army insignia painted on their chassis and arms.

Presidential metro sentinal unit
This unique sentry bot is encountered in Broken Steel, at the end of the Presidential metro, near the metro to Adams Air Force Base. It holds the main fuse, which needs to be used to repair the nearby powerbox for the metro.

Notable quotes
Sentry bots possess an authoritative array of speech programming, mainly expressing its current programming out loud, much like the protectron. However, sentry bots have a "deeper" voice, instilling fear in all.

Behind the scenes

 * Both the Enclave and Lyons' Brotherhood of Steel were supposed to have bots with unique textures. They are not used in the game, with both using the base steel sentry bot.

Bugs

 * Outcast sentry bots will always spawn with the Gatling laser arm, despite resources for the minigun variants being present.
 * A disabled sentry bot may be stuck in an animation loop if the animation did not finish when it was disabled.