Created by the RobCo corporation, protectron robots were designed (as their name suggests) for protection, although they can also be seen being used in a manual labor role as well. Typically used in office-type settings, their secondary programming is modular, making them useful as greeters, ticket collectors, bartenders, celebrity or historical figure impersonators, even sexual partners. In terms of combat, protectrons are usually weak and easy to defeat, because of their weak weapons and slow movement speed.
Some attributes of the protectrons looks were derived from 1950's comic books, the era in which many of Fallout's designs come from.
Many protectrons in various areas have been programmed differently. Other protectrons have even been supplied with sophisticated personalities, such as Primm Slim or Vendortron, but these are the exception rather than the average protectron.
A protectron with the basic personality loaded on it can execute 'sequences', lists of tasks to complete, such as patrolling an area for intruders. Some sequences may have been added by RobCo Industries, whereas others were written by robotics technicians at locations where they are used. When not in use, a protectron unit is stored in a base pod, which charges its battery. The protectron is connected to its base pod via radio uplink, and the pod is in turn connected to a control terminal or a computer system. Protectrons can be customized via software upgrades to perform specific functions, even outside their purpose. Such is the case with Fisto, a pre-War security bot who can be repurposed for sexual pursuits using the sex-bot holotape from Ralph at Mick & Ralph's, or the computer terminal in Cerulean Robotics for James Garret in Freeside during the quest "Wang Dang Atomic Tango".
There is also a non-functional prototype of the protectron named Protect-O-Bot, which can be found in the REPCONN headquarters museum, with wheels rather than normal legs, a dynamo accelerator, and a more car-type design.
Protectrons have about the same amount of health as an average human combatant but are much slower, making them less lethal. Their metal bodies provide them with a decent amount of armor protection,(a DT of 8) equal to a suit of metal armor in poor condition. They are equipped with a series of three built-in laser emitters, mounted in their right and left "hands", as well as the glowing dome atop their head. Unlike humans, protectrons do not take extra damage from head shots, although certain perks (such as Sniper) still make going for head shots a good option.
Like most robots, protectrons are much rarer in the Mojave Wasteland than in the Capital Wasteland. They are not found wandering the Wasteland at random, and are only encountered protecting a handful of intact pre-War facilities.
Protectrons, being one of the weaker robots in Fallout: New Vegas, and can be destroyed with most low-level weapons or explosives (such as frag grenades). Despite being somewhat more durable than the typical raider, their poor armor means their lifespan is likely to be quite short. They are gray by default, but often come painted or manufactured with colored parts depending on where they are found.
They have three laser weapons built into their frame, one in each arm and another one in their head. They are hardly the best shots, although sustained fire can put a dent in the player's health.
Like most robots, the protectron has a combat inhibitor on its back. Crippling this part of the robot will cause it to frenzy and start attacking all targets indiscriminately.
One of the weaker robots found in the Mojave Wasteland. They do not pose much of a threat, due to their slow speed as well as their weak damage. They are equipped with hand and head lasers, so if only one weapon is disabled, it is still combat effective. They are not as commonly found as in Fallout 3, with them being in every metro station. In Fallout: New Vegas they are patrolling some office buildings and the Securitron vault.
Shipping workers are robots found in the Sunset Sarsaparilla Headquarters. There are only two of them. They can be found on the bottom floor, in the large room of the factory with the bottle cap press machine. The same tactics work on them as well as normal protectrons. Once killed, scrap metal, energy cells and fission batteries may be found on their bodies. Several broken shipping workers are found throughout the headquarters, with each containing the same loot.
A slightly tougher variant of the protectron, three Sunset Sarsaparilla security protectrons can be found patrolling inside the Sunset Sarsaparilla Headquarters, defending it from all Wasteland intruders, while others that are already disabled can be scraped for components.
The Mark series of protectrons were an attempt by the Big MT company to reproduce, as well as improve, the protectrons produced by RobCo Industries before the war. The 'Mark' that is spawned depends on the player's level. The Mark I protectron is more sturdy than the RobCo models, the one exception being the one for security purposes at Sunset Sarsaparilla, but the Mark II upwards are all more durable than other models. However, the fire power on all models remains the same.
Unlike the variants found in Mojave, protectrons in Big MT have a higher DT.
A construction drone is a type of robot used in the Big MT. They were made as an alternative to human labor to manufacture the various structures and machinery seen in the Big MT. Due to their programming as a defensive robot, they also provide their own job site security, and are still operating after the Great War.
The protectrons of Fallout: New Vegas have a smoother, more automatic voice than those of Fallout 3.
Just like the sentry bots, the protectron has a melee weapon implemented, but doesn't use it in close combat either because it doesn't have an animation to script it, or because it relies on the more damaging laser weaponry.