羅伯科製造，正如名字所說，這種機器人是被設計來從事保衛工作的，也可以當作勞力，主要在辦公室中使用。它們的程序是模塊化的，通過改編，他們還可以勝任：迎賓，檢票員，售貨員，名人，演員甚至性伴侶等工作。這種機器人的多功能性要完全地歸功於這種機器人配備的多種人格程序，比較典型的幾種羅伯科提供的人格程序有：R04 V9「辦公助手」with the ability to process and track office protocols and agendas in real time、RS3 V4.1.6「雜務幫手」with automatic routine download and pest extermination mode和RX2 V1.16.4「避難所幫手」loaded with Vault protocols等。依據其功能的不同，不同的保安機器人配備的裝備也不一樣，醫療型機器人會配備電擊器、消防型機器人會配備冷凍槍、而警察型機器人則配備了電擊器和近戰模式，建築型機器人有時候也會配備有重型的射釘槍。戰鬥方面這種機器人菜的不行，走得慢且攻擊弱。
In the Commonwealth, protectrons are usually found in charging pods attached to terminals that must sometimes be hacked to activate them. The terminal software allows for different "personalities" to be uploaded to the unit, which changes the unit's voice dialogue and weapons loadout. The choices are: Default, Subway Steward, Construction Worker, Medical Responder, Firefighter, and Law Enforcement.
Some attributes of the protectron's looks were derived from 1950's comic books, which keeps with Fallout's overall retrofuturistic theme.
Factory protectrons are protectrons designed for use as manual labor inside of factories. Computer entries inside Sunset Sarsaparilla Headquarters in Fallout: New Vegas mention robots being shipped to the factory to replace the human workers. This is probably the case in Fallout 3 as well, and a few examples of these protectrons can be found inside The Mill in the Fallout 3 expansion The Pitt, although they are already deactivated.
Metro protectrons are a model of protectron found in Washington, D.C.'s metro stations that will ask for a passing person's metro ticket when activated, and that metro ticket will be removed from the inventory. If they do not happen to have a ticket, the protectron will attack.
Nuka-Cola security are protectrons found in the Nuka-Cola plant. They have the Nuka-Cola Corporation logo on them as well as red coloring around their head and hands. A deactivated one is found in Fallout: New Vegas, in the Lucky 38 penthouse.
Outcast protectrons are protectrons reprogrammed by the Brotherhood Outcasts. They are found patrolling with Outcast patrols or outside of their bases.
Factory protectron (The Pitt)
These factory protectrons are found in the Pitt steelyard and were being used as a replacement for human labor within the steel mills. They are heavy duty industrial robots, featuring a reinforced "head" part, a protective cage on the back and distinctive yellow coloring.
夕陽沙士保安比原版要稍稍難打一些，在夕陽沙士總部巡邏，Their function was to protect the factory, possibly against industrial espionage.地上也經常可以看到這種機器人的屍體。